Rechargeable aluminum ion battery

ABSTRACT

A rechargeable battery using a solution of an aluminum salt as an electrolyte is disclosed, as well as methods of making the battery and methods of using the battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/290,599, filed Oct. 11, 2016, which claims benefit under 35U.S.C. § 119 of U.S. Provisional Application Ser. No. 62/238,935, filedOct. 8, 2015, and a continuation-in-part of U.S. patent application Ser.No. 15/476,398, filed Mar. 31, 2017, which claims benefit under 35U.S.C. § 119 of U.S. Provisional Application Ser. No. 62/406,853, filedOct. 11, 2016, and which is a continuation-in-part of U.S. patentapplication Ser. No. 15/290,599, filed Oct. 11, 2016, which claimsbenefit under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No.62/238,935, filed Oct. 8, 2015 the contents of all of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to rechargeable batteries using chargecarriers comprising aluminum ions, and particularly batteries withreduced toxic components to minimize human health hazards andenvironmental damage.

Description of the Background

With an increase in interest in generating electricity from renewableenergy sources such as wind and solar, it has become increasinglyimportant to identify a viable battery storage system. Lead acidbatteries, for instance, are the most widely used battery technology forgrid storage owing to their low cost (about $100-$150/kWh). However,lead acid batteries have a comparatively low gravimetric energy density(30-50 Wh/kg) and a poor cycle life, between 500 and 1000charge/discharge cycles, based on the low depths of discharge (50-75%).In addition, lead acid batteries have significant safety problemsassociated with handling and disposal, due to the presence of sulfuricacid and toxic lead components. Reports of increased lead poisoning andacid-related injuries among workers and children exposed to unsafehandling and disposal of lead acid batteries, have raised strongconcerns over large-scale implementation of lead acid batteries asstorage for electricity generated from renewable energy sources.

The search for economical alternatives for electrical storage that lackthe environmental and health risks of lead acid batteries has not beensuccessful. One alternative, sodium ion batteries, are estimated toreach a price of about $250/kWh by 2020, but the volumetric energydensity of sodium ion battery technology is lower than that of lead acidbatteries at less than about 30 Wh/L.

Another alternative, vanadium redox flow batteries, offer high capacity,long discharge times and high cycle life, but have relatively lowgravimetric and volumetric energy densities, and are expensive due tothe high cost of vanadium and other components. Liquid metal batterieson the other hand are based on ion exchange between two immisciblemolten salt electrolytes, but must operate at high temperatures, up to450° C., rely on a complicated lead-antimony-lithium composite for ionexchange, and such systems have problems of flammability and toxicity.

SUMMARY OF THE INVENTION

A rechargeable battery using an electrolyte comprising aluminum ions isdisclosed, as well as methods of making the battery and methods of usingthe battery.

In certain embodiments, a battery is disclosed that includes an anodecomprising aluminum metal, an aluminum alloy or an aluminum compound, acathode, and an electrolyte comprising a solvent and an aluminum salt,and a porous separator comprising an electrically insulating materialthat prevents direct contact of the anode and the cathode. In preferredembodiments, the battery is a rechargeable battery.

In certain embodiments, a battery is disclosed that includes an anodecomprising aluminum, an aluminum alloy or an aluminum compound; acathode that comprises a material selected from the group consisting oflithium manganese oxide; acid-treated lithium manganese oxide;electrochemically delithiated lithium manganese oxide; hydrothermallydelithiated lithium manganese oxide; a lithium metal manganese oxide; anacid-treated lithium metal manganese oxide; a transition metal oxide; atransition metal sulfide; a transition metal nitride; a transition metalcarbide; an aluminum transition metal oxide; an aluminum transitionmetal sulfide; an aluminum transition metal nitride; an aluminumtransition metal carbide; a graphite metal composite; graphite-graphiteoxide; manganese dioxide; electrolytic manganese dioxide; sulfur; asulfur composite; phosphorus; a phosphorus composite; and graphene,wherein graphene is defined as carbon with fewer than one hundredsheets; and a porous separator comprising an electrically insulatingmaterial that prevents direct contact of the anode and the cathode; andan electrolyte comprising a solvent and an aluminum salt, wherein theelectrolyte is in contact with the anode and the cathode, and whereincharge is carried by an ion comprising aluminum during the discharge ofthe battery. In certain embodiments, the ion comprising aluminum isselected from the group consisting of Al³⁺, Al(OH)₄ ¹⁻, AlCl₄ ¹⁻, AlH₄¹⁻, AlF₆ ¹⁻, Al(NO₃)₄ ¹⁻, Al(SO₄)₂ ¹⁻, AlH₄ ¹⁻, AlF₄ ¹⁻, AlBr₄ ¹⁻, AlI₄¹⁻, Al(ClO₄)₄ ¹⁻, Al(PF₆)₄ ¹⁻, AlO₂ ¹⁻, Al(BF₄)₄ ¹⁻, and mixturesthereof. In certain embodiments, the solvent comprises at least onecompound selected from the group consisting of water, hydrogen peroxide,methanol, ethanol, isopropanol, acetone, tetrahydrofuran, N-methylpyrrolidone, a substituted or unsubstituted C₁-C₄ straight chain orbranched alkyl carbonate, a substituted or unsubstituted C₁-C₄ straightchain or branched alkene carbonate, an ionic liquid and mixturesthereof. In certain embodiments, the manganese dioxide has beensynthesized on a porous SiO₂ template.

In certain embodiments, the ionic liquid comprises at least one cationselected from the group consisting of a substituted or unsubstitutedquaternary ammonium ion, substituted or unsubstituted imidazolium ion, asubstituted or unsubstituted pyrrolidinium, a substituted orunsubstituted piperdinium, and a substituted or unsubstitutedphosphonium ion, and at least one anion selected from the groupconsisting of a halide ion, a carbonate ion, a nitrate ion, a sulfateion, a cyanate ion, a dicyanamide ion, a substituted or unsubstitutedborate ion, a substituted or unsubstituted acetate ion, a substituted orunsubstituted imide ion, a substituted or unsubstituted amide ion, asubstituted or unsubstituted sulfonate ion, and a substituted orunsubstituted benzoate ion, wherein when substituted, the substituent isat least one moiety selected from the group consisting of halide,carbonate, sulfate, substituted or unsubstituted C₁-C₄ straight chain orbranched alkyl, substituted or unsubstituted C₁-C₄ straight chain orbranched alkene, substituted or unsubstituted C₄-C₆ cycloalkyl, andsubstituted or unsubstituted C₆-C₈ aryl, and mixtures thereof.

In certain embodiments, the anode is an aluminum alloy comprisingaluminum metal and at least one of manganese, magnesium, lithium,zirconium, iron, cobalt, tungsten, vanadium, nickel, copper, silicon,chromium, titanium, tin and zinc. In certain embodiments, the anode isaluminum metal or an aluminum alloy that has received a surfacetreatment to increase its hydrophilic properties. In certainembodiments, the surface treatment comprises the step of contacting asurface of the aluminum with an aqueous solution of an alkali metalhydroxide. In certain embodiments, anode is an aluminum metal foil or analuminum alloy foil.

In certain embodiments, the anode is an aluminum compound selected fromthe group consisting of an aluminum transition metal oxide(Al_(x)M_(y)O_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive), an aluminum transition metal sulfide(Al_(x)M_(y)S_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive), an aluminum transition metal nitride(Al_(x)M_(y)N_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive), an aluminum transition metal carbide(Al_(x)M_(y)C_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive), aluminum lithium cobalt oxide, lithium aluminumhydride, sodium aluminum hydride, potassium aluminum fluoride, aluminumindium oxide, aluminum gallium oxide, aluminum indium sulfide, aluminumgallium sulfide, aluminum indium nitride, aluminum gallium nitride, andmixtures thereof.

In certain embodiments, the anode is treated with a reagent selectedfrom the group consisting of alkali metal hydroxides, alkali metalphosphates, alkali metal phosphides, alkali metal nitrates, alkali metalnitrides, alkali metal sulfates, alkali metal sulfides of alkali metalsand mixtures thereof, wherein the alkali metal is at least one oflithium, sodium, potassium, calcium, rubidium, or cesium. In certainembodiments, the anode is treated with phosphoric acid, nitric acid,sulfuric acid, sulfurous acid, acetic acid, hydrochloric acid,hydrofluoric acid, hydrogen peroxide, polyvinyl alcohol, ozone, oxygenplasma etching or laser etching.

In certain embodiments, the anode comprises aluminum coated with a metaloxide layer, aluminum coated with a metal phosphate layer, aluminumcoated with a metal nitride layer, aluminum coated with a metal sulfidelayer, or aluminum coated with a metal carbide layer, wherein the metalis selected from the group consisting of titanium, molybdenum, cobalt,tin, vanadium, ruthenium, palladium, copper, nickel, zinc, iron,manganese, chromium, silver, gold, platinum and mixtures thereof. Incertain embodiments, the anode is coated with a layer of ionicallyconducting, insulating or electrically conductive polymer selected fromthe group consisting of a polyaniline, a polyacetylene, a polyphenylenevinylene, a parylene, a polypyrrole, a polythiophene, a polyphenylenesulfide, a polystyrene, a polyvinyl alcohol, a polyethylene oxide, apolymethyl methacrylate, graphite and mixtures thereof. Suitable coatingmethods are known in the art, including spin coating, drop casting,spray coating, chemical vapor deposition, and coating pastes of thepolymer with doctor-blade or slot-die methods.

In certain embodiments, the anode further comprises a redox catalystsuch as platinum, a compound comprising zirconium, vanadium pentoxide,silver oxide, iron oxide, molybdenum oxide, bismuth oxide,bismuth-molybdenum oxide, iron molybdenum oxide, palladium salts, coppersalts, cobalt salts, manganese salts, Prussian blue analogs such ascobalt hexacyanocobaltate or manganese hexacyanocobaltate, and mixturesthereof.

In certain embodiments, the solvent comprises at least one compoundselected from the group consisting of water, hydrogen peroxide,methanol, ethanol, isopropanol, acetone, tetrahydrofuran, N-methylpyrrolidone, a substituted or unsubstituted C₁-C₄ straight chain orbranched alkyl carbonate, a substituted or unsubstituted C₁-C₄ straightchain or branched alkene carbonate, an ionic liquid comprising at leastone cation selected from the group consisting of a substituted orunsubstituted quaternary ammonium ion, substituted or unsubstitutedimidazolium ion, a substituted or unsubstituted pyrrolidinium, asubstituted or unsubstituted piperdinium, and a substituted orunsubstituted phosphonium ion, and at least one anion selected from thegroup consisting of a halide ion, a carbonate ion, a nitrate ion, asulfate ion, a cyanate ion, a dicyanamide ion, a substituted orunsubstituted borate ion, a substituted or unsubstituted acetate ion, asubstituted or unsubstituted imide ion, a substituted or unsubstitutedamide ion, a substituted or unsubstituted sulfonate ion, and asubstituted or unsubstituted benzoate ion, wherein when substituted, thesubstituent is at least one moiety selected from the group consisting ofhalide, carbonate, sulfate, substituted or unsubstituted C₁-C₄ straightchain or branched alkyl, substituted or unsubstituted C₁-C₄ straightchain or branched alkene, substituted or unsubstituted C₄-C₆ cycloalkyl,and substituted or unsubstituted C₆-C₈ aryl, and mixtures thereof.

In certain embodiments, the solvent comprises at least one compoundselected from the group consisting of water, hydrogen peroxide,methanol, ethanol, isopropanol, acetone, tetrahydrofuran, N-methylpyrrolidone, dimethyl carbonate, diethyl carbonate, ethylene carbonate,propylene carbonate, a fluorocarbonate, a glycol, a methyl imide,phosphinate, amine, an imidazolium acetate, an imidazolium aluminate, animidazolium carbonate, an imidazolium cyanate, an imidazoliumdicyanamide, an imidazolium halide, an imidazolium hexafluorophosphate,an imidazolium imide, an imidazolium nitrate, an imidazolium phosphate,an imidazolium sulfate, an imidazolium sulfonate, an imidazoliumtetrafluoroborate, an imidazolium tosylate, a pyrrolidinium halide, apyrrolidinium imide, a pyrrolidinium tetrafluoroborate, atetrabutylammonium benzoate, a tetrabutylammonium cyanate, atetrabutylammonium halide, preferably tetrabutylammonium bromide, atetrabutylammonium sulfonate, a tetrabutylammonium trifluoroacetate, aphosphonium tetrafluoroborate, preferably tetrabutylphosphoniumtetrafluoroborate, phosphonium, a phosphonium halide, a phosphoniumsulfonate, a phosphonium tosylate and mixtures thereof.

In certain embodiments, the aluminum salt is selected from the groupconsisting of aluminum bromide hexahydrate, aluminum fluoride, aluminumfluoride trihydrate, aluminum iodide, aluminum iodide hexahydrate,aluminum perchlorate, aluminum hydroxide, aluminum acetate, aluminumacetoacetate, aluminum nitrate, aluminum nitrate nonahydrate, aluminumantimonide, aluminum arsenate, aluminum bromide, aluminum sulfate,aluminum phosphate, aluminum carbonate, aluminum chloride, aluminumchlorohydrate, aluminum clofibrate, aluminum diacetate, aluminumdiboride, aluminum diethyl phosphinate, aluminum formate, aluminumgallium arsenide, aluminum gallium indium phosphide, aluminum galliumnitride, aluminum gallium phosphide, aluminum indium arsenide, aluminumiodide, aluminum magnesium boride, aluminum molybdate, aluminum bromide,aluminum iodide, aluminum oxide, aluminum oxynitride, aluminum silicate,aluminoxane, ammonium aluminum sulfate, ammonium hexafluoroaluminate andmixtures thereof.

In further embodiments, the aluminum salt is selected from the groupconsisting of aluminum acetate, aluminum acetoacetate, aluminumantimonide, aluminum arsenate, aluminum bromide, aluminum bromidehexahydrate, aluminum carbonate, aluminum chloride, aluminumchlorohydrate, aluminum clofibrate, aluminum diacetate, aluminum diethylphosphinate, aluminum fluoride, aluminum fluoride trihydrate, aluminumformate, aluminum gallium arsenide, aluminum gallium indium phosphide,aluminum gallium nitride, aluminum gallium phosphide, aluminumhydroxide, aluminum indium arsenide, aluminum iodide, aluminum iodidehexahydrate, aluminum molybdate, aluminum nitrate, aluminum nitratenonahydrate, aluminum oxide, aluminum perchlorate, aluminum phosphate,aluminum silicate, aluminoxane, ammonium aluminum sulfate and mixturesthereof.

In other embodiments, the aluminum salt is selected from the groupconsisting of aluminum acetate, aluminum acetoacetate, aluminum bromide,aluminum bromide hexahydrate, aluminum carbonate, aluminum chloride,aluminum chlorohydrate, aluminum clofibrate, aluminum diacetate,aluminum diethyl phosphinate, aluminum fluoride, aluminum fluoridetrihydrate, aluminum formate, aluminum hydroxide, aluminum iodide,aluminum iodide hexahydrate, aluminum molybdate, aluminum nitrate,aluminum nitrate nonahydrate, aluminum perchlorate, aluminum phosphate,aluminum silicate, aluminum sulfate, aluminum sulfide, aluminoxane,ammonium aluminum sulfate, ammonium hexafluoroaluminate and mixturesthereof.

In certain embodiments, the electrolyte further comprises lithiumbis(trifluoromethanesulfonyl)imide, diethyl carbonate and dimethylcarbonate. In certain embodiments, the electrolyte further comprises atleast one ion selected from the group consisting of Li¹⁺, Cl¹⁻, and CH₃¹⁺. In certain embodiments, the charge is carried by an ion selectedfrom the group consisting of Li¹⁺, Cl¹⁻, and CH₃ ¹⁺ during the dischargeof the battery.

In certain embodiments, the electrolyte further comprises at least onecompound selected from the group consisting of lithium hydroxide, sodiumhydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide,magnesium hydroxide, rubidium oxide, cesium oxide,polytetrafluoroethylene, polyethylene oxide, acetonitrile butadienestyrene, styrene butadiene rubber, ethyl vinyl acetate, polyvinylalcohol, poly(vinylidene fluoride-co-hexafluoropropylene), polymethylmethacrylate and mixtures thereof.

Typically the molarity of the aluminum salt ranges from 0.05 M to 5 Mand the concentration of water ranges from 5 weight % to 95 weight %.

In certain embodiments, the electrolyte is an aqueous solution of analuminum salt selected from the group consisting of aluminum bromidehexahydrate, aluminum fluoride, aluminum fluoride trihydrate, aluminumiodide, aluminum iodide hexahydrate, aluminum perchlorate, aluminumhydroxide, aluminum acetate, aluminum acetoacetate, aluminum nitrate,aluminum nitrate nonahydrate, aluminum antimonide, aluminum arsenate,aluminum bromide, aluminum sulfate, aluminum phosphate, aluminumcarbonate, aluminum chloride, aluminum chlorohydrate, aluminumclofibrate, aluminum diacetate, aluminum diboride, aluminum diethylphosphinate, aluminum formate, aluminum gallium arsenide, aluminumgallium indium phosphide, aluminum gallium nitride, aluminum galliumphosphide, aluminum indium arsenide, aluminum iodide, aluminum magnesiumboride, aluminum molybdate, aluminum bromide, aluminum iodide, aluminumoxide, aluminum oxynitride, aluminum silicate, aluminoxane, ammoniumaluminum sulfate, ammonium hexafluoroaluminate and mixtures thereof. Infurther embodiments, the electrolyte is an aqueous solution of analuminum salt is selected from the group consisting of aluminum bromidehexahydrate, aluminum fluoride, aluminum fluoride trihydrate, aluminumiodide, aluminum iodide hexahydrate, aluminum perchlorate, aluminumhydroxide, aluminum acetate, aluminum acetoacetate, aluminum nitrate,aluminum nitrate nonahydrate, aluminum antimonide, aluminum arsenate,aluminum bromide, aluminum sulfate, aluminum phosphate, aluminumcarbonate, aluminum chloride, aluminum chlorohydrate, aluminumclofibrate, aluminum diacetate, aluminum diethyl phosphinate, aluminumformate, aluminum gallium arsenide, aluminum gallium indium phosphide,aluminum gallium nitride, aluminum gallium phosphide, aluminum indiumarsenide, aluminum iodide, aluminum molybdate, aluminum bromide,aluminum iodide, aluminum oxide, aluminum silicate, aluminoxane,ammonium aluminum sulfate and mixtures thereof.

In other embodiments, the electrolyte is an aqueous solution of analuminum salt selected from the group consisting of aluminum bromidehexahydrate, aluminum fluoride, aluminum fluoride trihydrate, aluminumiodide, aluminum iodide hexahydrate, aluminum perchlorate, aluminumhydroxide, aluminum acetate, aluminum acetoacetate, aluminum nitrate,aluminum nitrate nonahydrate, aluminum bromide, aluminum sulfate,aluminum phosphate, aluminum carbonate, aluminum chloride, aluminumchlorohydrate, aluminum clofibrate, aluminum diacetate, aluminum diethylphosphinate, aluminum formate, aluminum iodide, aluminum molybdate,aluminum bromide, aluminum iodide, aluminum silicate, aluminoxane,ammonium aluminum sulfate, and mixtures thereof.

In certain embodiments, the electrolyte further comprises at least oneof polytetrafluoroethylene, polyethylene oxide, acetonitrile butadienestyrene, styrene butadiene rubber, ethyl vinyl acetate, polyvinylalcohol, poly(vinylidene fluoride-co-hexafluoropropylene), polymethylmethacrylate and mixtures thereof. The molarity of the aluminum saltranges from 0.05 M to 5 M and the concentration of water ranges from 5weight % to 95 weight %.

In certain embodiments, the electrolyte comprises at least two ionsselected from the group consisting of Al³⁺, Li¹⁺, Al(OH)₄ ¹⁻, AlCl₄ ¹⁻,AlH₄ ¹⁻, AlF₆ ¹⁺, Al(NO₃)₄ ¹⁻, Al(SO₄)₂ ¹⁻, AlH₄ ¹⁻, AlF₄ ¹⁻, AlBr₄ ¹⁻,AlI₄ ¹⁻, Al(ClO₄)₄ ¹⁻, Al(PF₆)₄ ¹⁻, AlO₂ ¹⁻, Al(BF₄)₄ ¹⁻, Cl¹⁻, and CH₃¹⁺.

In certain embodiments, the cathode comprises a material selected fromthe group consisting of lithium manganese oxide, acid-treated lithiummanganese oxide, lithium metal manganese oxide (where the metal can benickel, cobalt, aluminum, chromium, sodium, potassium, iron, copper,tin, titanium, tungsten, zinc, platinum and combinations thereof),acid-treated lithium metal manganese oxide, transition metal oxide(where the metals include, but are not limited to iron, vanadium,titanium, molybdenum, copper, nickel, zinc, tungsten, manganese,chromium, cobalt and mixtures thereof), transition metal sulfide (wherethe metals include, but are not limited to iron, vanadium, titanium,molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, cobaltand mixtures thereof), transition metal nitride (where the metals couldinclude, but are not limited to iron, vanadium, titanium, molybdenum,copper, nickel, zinc, tungsten, manganese, chromium, cobalt and mixturesthereof), transition metal carbide (where the metals could include, butare not limited to iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, cobalt and mixtures thereof),aluminum transition metal oxide, aluminum transition metal sulfide,aluminum transition metal nitride, aluminum transition metal carbide,graphite metal composite (where the metal can be conductive metalsincluding but not limited to nickel, iron, copper, cobalt, chromium,aluminum, sodium, potassium, iron, copper, tin, titanium, tungsten,zinc, platinum, gold, silver), graphite-graphite oxide, manganesedioxide, electrolytic manganese dioxide, sulfur, sulfur composites(where the composites may include carbon, aluminum, lithium, iron,vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt, sodium, potassium, tin, platinum, manganesedioxide), phosphorus, phosphorus composites (where the composites mayinclude carbon, aluminum, lithium, iron, vanadium, titanium, molybdenum,copper, nickel, zinc, tungsten, manganese, chromium, cobalt, sodium,potassium, tin, platinum, manganese dioxide), and graphene, wheregraphene is defined as carbon with fewer than one hundred sheets.

In certain embodiments, the cathode comprises a material selected fromthe group consisting of a lithium metal manganese oxide, wherein themetal is selected from the group consisting of nickel, cobalt, aluminum,chromium, sodium, potassium, iron, copper, tin, titanium, tungsten,zinc, platinum and mixtures thereof; an acid-treated lithium metalmanganese oxide, wherein the metal is selected from the group consistingof nickel, cobalt, aluminum, chromium, sodium, potassium, iron, copper,tin, titanium, tungsten, zinc, platinum and mixtures thereof; atransition metal oxide, wherein the transition metal is selected fromthe group consisting of iron, vanadium, titanium, molybdenum, copper,nickel, zinc, tungsten, manganese, chromium, cobalt and mixturesthereof; a transition metal sulfide, wherein the transition metal isselected from the group consisting of iron, vanadium, titanium,molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, cobaltand mixtures thereof; a transition metal nitride, wherein the transitionmetal is selected from the group consisting of iron, vanadium, titanium,molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, cobaltand mixtures thereof; a transition metal carbide, wherein the transitionmetal is selected from the group consisting of iron, vanadium, titanium,molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, cobaltand mixtures thereof; an aluminum transition metal oxide, wherein thetransition metal is selected from the group consisting of iron,vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt and mixtures thereof; an aluminum transitionmetal sulfide, wherein the transition metal is selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, cobalt and mixtures thereof; analuminum transition metal nitride, wherein the transition metal isselected from the group consisting of iron, vanadium, titanium,molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, cobaltand mixtures thereof; an aluminum transition metal carbide, wherein thetransition metal is selected from the group consisting of iron,vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt and mixtures thereof; a graphite metalcomposite, wherein the metal is an electrically conductive metalselected from the group consisting of nickel, iron, copper, cobalt,chromium, aluminum, sodium, potassium, iron, copper, tin, titanium,tungsten, zinc, platinum, gold, silver; a sulfur composite, wherein thesulfur composite comprises an element selected from the group consistingof carbon, aluminum, lithium, iron, vanadium, titanium, molybdenum,copper, nickel, zinc, tungsten, manganese, chromium, cobalt, sodium,potassium, tin, platinum or manganese dioxide; and a phosphoruscomposite, wherein the phosphorus composite comprises an elementselected from the group consisting of carbon, aluminum, lithium, iron,vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt, sodium, potassium, tin, platinum, ormanganese dioxide; and mixtures thereof.

In certain embodiments, the cathode comprises acid-treated lithiummanganese oxide that has been treated using iron oxide nanoparticles ina magnetic field.

In certain embodiments, the cathode further includes a redox catalystsuch as platinum, a compound comprising zirconium, vanadium pentoxide,silver oxide, iron oxide, molybdenum oxide, bismuth oxide,bismuth-molybdenum oxide, iron molybdenum oxide, palladium salts, coppersalts, cobalt salts, manganese salts, Prussian blue analogs and mixturesthereof.

In certain embodiments, lithium manganese oxide, acid-treated lithiummanganese oxide, electrochemically delithiated lithium manganese oxide,lithium metal manganese oxide, acid-treated lithium metal manganeseoxide, transition metal oxide, transition metal sulfide, transitionmetal nitride, transition metal carbide, aluminum transition metaloxide, aluminum transition metal sulfide, aluminum transition metalnitride, aluminum transition metal carbide, graphite metal composite,graphite-graphite oxide, manganese dioxide, electrolytic manganesedioxide, sulfur composites, phosphorus composites, and graphene maybefurther mixed with a metal such as copper, nickel, iron, zinc, lithium,sodium, potassium, magnesium, titanium, vanadium, chromium, molybdenum,tungsten, manganese, cobalt, indium, aluminum and lead, a semi-metal ormetalloid such as boron, silicon and germanium, zeolite,polymethylmethacrylate, polyethylene oxide, polyvinyl alcohol,polyaniline, polyvinyldifluoride, polytetrafluoroethylene, and oxides,phosphates, phosphides, sulfates, sulfides, nitrates, nitrides,hydroxides and carbonates of metals and metalloids. In certain preferredembodiments, the morphology of the metal, semi-metal, zeolite or oxide,hydroxide, sulfate, nitrate, phosphate, carbonates and halides may be inthe form of hollow tubes, hollow spheres and hollow cubes. In certainembodiments, the metal, semi-metal, zeolite or oxide, hydroxide,sulfate, nitrate, phosphate, carbonates and halides may be crystalline,amorphous or polymorphous. In certain preferred embodiments, the metal,semi-metal, zeolite, polymethylmethacrylate, polyethylene oxide,polyvinyl alcohol, polyaniline, polyvinyldifluoride,polytetrafluoroethylene, or an oxide, hydroxide, sulfate, nitrate,phosphate, carbonates and halides of the metal or metalloid may beremoved through wet or dry etching or through thermal decomposition ofpolymers to create a porous cathode template with increasedhydrophilicity.

In certain embodiments, the cathode is further subject to a surfacetreatment with at least one of hydroxides, phosphates, phosphides,nitrates, nitrides, sulfates, sulfides of alkali metals where the alkalimetals include at least one of lithium, sodium, potassium, calcium,rubidium, cesium, phosphoric acid, nitric acid, sulfuric acid, sulfurousacid, acetic acid, hydrochloric acid, hydrofluoric acid, hydrogenperoxide, ozone, oxygen plasma etching, electrochemical delithiation,hydrothermal delithiation, and laser etching.

In certain preferred embodiments, the lithium manganese oxide has beensubjected to acid treatment. In certain preferred embodiments, the anodecomprises aluminum metal, the cathode comprises graphite-graphite oxide,and the aluminum salt comprises aluminum nitrate. In other preferredembodiments, the anode comprises aluminum metal, the cathode comprisesdelithiated lithium manganese oxide, and the aluminum salt comprisesaluminum nitrate.

In certain embodiments, a battery is disclosed that includes an anodecomprising aluminum, an aluminum alloy or an aluminum compound; acathode that comprises a material selected from the group consisting oflithium manganese oxide; acid-treated lithium manganese oxide;electrochemically delithiated lithium manganese oxide; hydrothermallydelithiated lithium manganese oxide; a lithium metal manganese oxide; anacid-treated lithium metal manganese oxide; a transition metal oxide; atransition metal sulfide; a transition metal nitride; a transition metalcarbide; an aluminum transition metal oxide; an aluminum transitionmetal sulfide; an aluminum transition metal nitride; an aluminumtransition metal carbide; a graphite metal composite; graphite-graphiteoxide; manganese dioxide; electrolytic manganese dioxide; sulfur; asulfur composite; phosphorus; a phosphorus composite; and graphene,wherein graphene is defined as carbon with fewer than one hundredsheets; and an electrolyte comprising a polymer selected from the groupconsisting of polytetrafluoroethylene, acetonitrile butadiene styrene,styrene butadiene rubber, ethyl vinyl acetate, poly(vinylidenefluoride-co-hexafluoropropylene), polymethyl methacrylate, and mixturesthereof; and an aluminum salt selected from the group consisting ofaluminum nitrate, aluminum nitrate nonahydrate, aluminum sulfate,aluminum phosphate, aluminum bromide hexahydrate, aluminum fluoride,aluminum fluoride trihydrate, aluminum iodide, aluminum iodidehexahydrate, aluminum perchlorate, aluminum hydroxide, aluminum acetate,aluminum acetoacetate, aluminum bromide, aluminum carbonate, aluminumchloride, aluminum chlorohydrate, aluminum clofibrate, aluminumdiacetate, aluminum diethyl phosphinate, aluminum formate, aluminumiodide, aluminum molybdate, aluminum bromide, aluminum iodide, aluminumsilicate, aluminum sulfide, aluminoxane, ammonium aluminum sulfate,ammonium hexafluoroaluminate and mixtures thereof, wherein theelectrolyte is in contact with the anode and the cathode, and whereincharge is carried by an ion comprising aluminum during the discharge ofthe battery.

In certain embodiments, a battery is disclosed that comprises an anodecomprising aluminum, an aluminum alloy selected from the groupcomprising of aluminum and at least one of manganese, magnesium,lithium, zirconium, iron, cobalt, tungsten, vanadium, nickel, copper,silicon, chromium, titanium, tin and zinc or an aluminum compoundselected from the group consisting of an aluminum transition metal oxide(Al_(x)M_(y)O_(z), where M is the transition metal including but notlimited to iron, vanadium, titanium, molybdenum, copper, nickel, zinc,tungsten, manganese, chromium, cobalt), an aluminum transition metalsulfide (Al_(x)M_(y)S_(z)), an aluminum transition metal nitride, analuminum transition metal carbide, aluminum lithium cobalt oxide(AlLi₃CoO₂), lithium aluminum hydride (LiAlH₄), sodium aluminum hydride(NaAlH₄), potassium aluminum fluoride (KAlF₄), aluminum oxidescontaining another semi-metal or metal species, such as aluminum indiumoxide or aluminum gallium oxide, aluminum sulfides containing anothersemi-metal or metal species, such as aluminum indium sulfide andaluminum gallium sulfide, aluminum nitrides containing anothersemi-metal or metal species, such as aluminum indium nitride or aluminumgallium nitride, aluminum coated with a metal oxide layer, aluminumcoated with a metal phosphate layer, aluminum coated with a metalnitride layer, aluminum coated with a metal sulfide layer, aluminumcoated with a metal carbide layer, aluminum coated with a graphite layerand mixtures thereof; a cathode comprising a material selected from thegroup consisting of lithium manganese oxide, acid-treated lithiummanganese oxide, lithium metal manganese oxide (where the metal can benickel, cobalt, aluminum, chromium, sodium, potassium, iron, copper,tin, titanium, tungsten, zinc, platinum and combinations thereof),acid-treated lithium metal manganese oxide, transition metal oxide,transition metal sulfide, transition metal nitride, transition metalcarbide, aluminum transition metal oxide, aluminum transition metalsulfide, aluminum transition metal nitride, aluminum transition metalcarbide, graphite metal composite (where the metal can be conductivemetals including but not limited to nickel, iron, copper, cobalt,chromium, aluminum, sodium, potassium, iron, copper, tin, titanium,tungsten, zinc, platinum, gold, silver), graphite-graphite oxide,manganese dioxide, electrolytic manganese dioxide, sulfur, sulfurcomposites, phosphorus, phosphorus composites and graphene; and anelectrolyte comprising an aqueous solution of an aluminum salt selectedfrom the group consisting of aluminum bromide hexahydrate, aluminumfluoride, aluminum fluoride trihydrate, aluminum iodide, aluminum iodidehexahydrate, aluminum perchlorate, aluminum hydroxide, aluminum acetate,aluminum acetoacetate, aluminum nitrate, aluminum nitrate nonahydrate,aluminum bromide, aluminum sulfate, aluminum phosphate, aluminumcarbonate, aluminum chloride, aluminum chlorohydrate, aluminumclofibrate, aluminum diacetate, aluminum diethyl phosphinate, aluminumformate, aluminum iodide, aluminum molybdate, aluminum bromide, aluminumiodide, aluminum silicate, aluminoxane, ammonium aluminum sulfate, andmixtures thereof. Typically, the battery further comprises a porousseparator comprising an electrically insulating material that preventsdirect contact of the anode and the cathode.

In certain embodiments, a battery is disclosed that includes an anodecomprising aluminum metal; an aluminum alloy comprising aluminum and atleast one selected from the group consisting of manganese, magnesium,lithium, zirconium, iron, cobalt, tungsten, vanadium, nickel, copper,silicon, chromium, titanium, tin and zinc; or an aluminum compoundselected from the group consisting of an aluminum transition metal oxide(Al_(x)M_(y)O_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); an aluminum transition metal sulfide(Al_(x)M_(y)S_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); an aluminum transition metal nitride(Al_(x)M_(y)N_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); an aluminum transition metal carbide(Al_(x)M_(y)C_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); aluminum lithium cobalt oxide, lithium aluminumhydride, sodium aluminum hydride, potassium aluminum fluoride, aluminumindium oxide, aluminum gallium oxide, aluminum indium sulfide, aluminumgallium sulfide, aluminum indium nitride, aluminum gallium nitride, andmixtures thereof; a cathode comprising a material selected from thegroup consisting of lithium manganese oxide, graphite-graphite oxide,manganese dioxide and graphene; a porous separator that prevents directcontact of the anode and the cathode wherein the porous separatorcomprises an electrically insulating material selected from the groupconsisting of polyethylene, polytetrafluoroethylene, polyvinyl chloride,ceramic, polyester, rubber, polyolefins, glass mat, polypropylene, amixed cellulose ester, nylon, glass microfiber and mixtures andcombinations thereof; and an electrolyte comprising an aluminum saltselected from the group consisting of aluminum nitrate, aluminumsulfate, aluminum phosphate, aluminum bromide hexahydrate, aluminumfluoride, aluminum fluoride trihydrate, aluminum iodide hexahydrate,aluminum perchlorate, aluminum hydroxide, and combinations thereof and asolvent comprising at least one compound selected from the groupconsisting of water, hydrogen peroxide, methanol, ethanol, isopropanol,acetone, tetrahydrofuran, N-methyl pyrrolidone, dimethyl carbonate,diethyl carbonate, ethylene carbonate, propylene carbonate, animidazolium acetate, an imidazolium aluminate, an imidazolium carbonate,an imidazolium cyanate, an imidazolium dicyanamide, an imidazoliumhalide, an imidazolium hexafluorophosphate, an imidazolium imide, animidazolium nitrate, an imidazolium phosphate, an imidazolium sulfate,an imidazolium sulfonate, an imidazolium tetrafluoroborate, animidazolium tosylate, a pyrrolidinium halide, a pyrrolidinium imide, apyrrolidinium tetrafluoroborate, a tetrabutylammonium benzoate, atetrabutylammonium cyanate, a tetrabutylammonium halide, preferablytetrabutylammonium bromide, a tetrabutylammonium sulfonate, atetrabutylammonium trifluoroacetate, a phosphonium tetrafluoroborate,preferably tetrabutylphosphonium tetrafluoroborate, a phosphoniumhalide, a phosphonium sulfonate, a phosphonium tosylate and mixturesthereof.

In certain embodiments, the anode and cathode are coated onto a currentcollector where the collector is a metal or a conductive non-metal thatincludes at least one of nickel, copper, aluminum, stainless steel,vanadium, titanium, molybdenum, carbon, tin, brass, gold and palladium.The current collector may be further subject to surface treatment, priorto electrode coating, in order to improve adhesion. Such treatmentsinclude surface etching in an acidic solution, iron chloride solution oran alkali metal hydroxide solution, buffer oxide etchant, piranhasolution, plasma etching, gas etching, laser etching, ion implantation.In certain embodiments the anode and cathode are coated on to a porouspolymer separator membrane. In certain embodiments, the anode andcathode are free standing, such as in the form of a foil, a sheet or aplate. In certain embodiments, the anode and cathode are delaminatedfrom the current collector after coating and drying of the electrode byusing at least one of a surface etchant such as alkali metal hydroxides,acids, buffer oxide etchant and piranha solution (a mixture ofconcentrated sulfuric acid with hydrogen peroxide, in a ratio of 3:1 to7:1). In certain other embodiments, the anode is free-standing, such asin the form of a foil, a sheet or a plate, while the cathode is coatedon to a current collector.

Also disclosed are methods of using a rechargeable battery that includesan anode comprising aluminum, an aluminum alloy or an aluminum compound,a cathode, and an electrolyte comprising an aqueous solution of analuminum salt. In certain embodiments, a system is disclosed thatincludes at least one such rechargeable battery that is operativelyconnected to a controller, and wherein the controller is operativelyconnected to a source of electrical power and to a load. In certainembodiments, the controller is effective to control the charging of thebattery by the source of electrical power. In certain embodiments, thecontroller is effective to control the discharging of the battery by theload. In certain embodiments, the source of electrical power is a solarpanel or wind-powered generator. In certain embodiments, the load is alocal electrical load or a power distribution grid.

In certain embodiments, a method is disclosed that includes the steps ofcontacting lithium manganese oxide powder with an excess volume of anacid selected from the group consisting of nitric acid, hydrochloricacid, sulfuric acid, acetic acid, hydroiodic acid, phosphoric acid andmixtures thereof to form a suspension; and filtering the suspension torecover delithiated lithium manganese oxide. In certain embodiments, amethod also includes the step of contacting the delithiated manganeseoxide with a 0.1-4 M hydroxide solution selected from the groupconsisting of lithium hydroxide, potassium hydroxide, sodium hydroxide,tetramethyl ammonium hydroxide and mixtures thereof. In certainembodiments, the hydroxide solution further comprises a solvent selectedfrom the group consisting of water, ethanol, N-methyl pyrrolidone andmixtures thereof.

In certain embodiments, a method is disclosed that includes the steps ofthe steps of combining 2-98 wt % lithium manganese oxide with 0-20 wt %(based on the total weight of the mixture) of a polymer binder selectedfrom the group consisting of polyvinylidene fluoride,polytetrafluoroethylene, styrene-butadiene rubber and mixtures thereofto form a mixture; combining the mixture with a solvent selected fromthe group consisting of water, ethanol, N-methyl pyrrolidone, dimethylsulfoxide and mixtures thereof and mixing to form a slurry; casting theslurry on a substrate selected from the group consisting of aluminum,stainless steel, nickel, copper and pyrolytic graphite; drying theslurry and the substrate to form a cathode; placing the cathode in anelectrochemical cell having a lithium foil electrode, a lithium ionelectrolyte and a separator; and applying a voltage between the cathodeand the lithium foil electrode to produce a cathode comprisingdelithiated lithium manganese oxide. In certain embodiments, the mixturefurther comprises 0-20 wt % (based on the total weight of the mixture)of a thickening agent that is polysaccharide gum. In certainembodiments, the mixture further comprises 0-50 wt % (based on the totalweight of the mixture) of a conductive carbon additive selected from thegroup consisting of activated carbon, Super-P carbon and mixturesthereof. In certain embodiments, the mixture comprises 80 wt % lithiummanganese oxide, 6 wt % styrene-butadiene rubber, and further comprises4 wt % carboxymethyl cellulose and 10 wt % Super-P conductive carbon(based on the total weight of the mixture).

In certain embodiments, a method is disclosed that includes the steps ofcombining a material selected from the group consisting of a metal oxideselected from the group consisting of lithium manganese oxide,delithiated lithium manganese oxide, manganese dioxide, titanium oxide,tin oxide, iron oxide, vanadium oxide, molybdenum oxide, cobalt oxideand mixtures thereof; an aluminum transition metal oxide(Al_(x)M_(y)O_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); an aluminum transition metal sulfide(Al_(x)M_(y)S_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); an aluminum transition metal nitride(Al_(x)M_(y)N_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); an aluminum transition metal carbide(Al_(x)M_(y)C_(z), where M is a transition metal selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z rangefrom 0 to 8, inclusive); aluminum lithium cobalt oxide, lithium aluminumhydride, sodium aluminum hydride, potassium aluminum fluoride, aluminumindium oxide, aluminum gallium oxide, aluminum indium sulfide, aluminumgallium sulfide, aluminum indium nitride, aluminum gallium nitride, andmixtures thereof; a redox catalyst selected from the group consisting ofplatinum, a compound comprising zirconium, vanadium pentoxide, silveroxide, iron oxide, molybdenum oxide, bismuth oxide, bismuth-molybdenumoxide, iron molybdenum oxide, palladium salts, copper salts, cobaltsalts, manganese salts, Prussian blue analogs such as cobalthexacyanocobaltate or manganese hexacyanocobaltate, and mixturesthereof; a lithium metal manganese oxide, wherein the metal is selectedfrom the group consisting of nickel, cobalt, aluminum, chromium, sodium,potassium, iron, copper, tin, titanium, tungsten, zinc, platinum andmixtures thereof; an acid-treated lithium metal manganese oxide, whereinthe metal is selected from the group consisting of nickel, cobalt,aluminum, chromium, sodium, potassium, iron, copper, tin, titanium,tungsten, zinc, platinum and mixtures thereof; a transition metal oxide,wherein the transition metal is selected from the group consisting ofiron, vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt and mixtures thereof; a transition metalsulfide, wherein the transition metal is selected from the groupconsisting of iron, vanadium, titanium, molybdenum, copper, nickel,zinc, tungsten, manganese, chromium, cobalt and mixtures thereof; atransition metal nitride, wherein the transition metal is selected fromthe group consisting of iron, vanadium, titanium, molybdenum, copper,nickel, zinc, tungsten, manganese, chromium, cobalt and mixturesthereof; a transition metal carbide, wherein the transition metal isselected from the group consisting of iron, vanadium, titanium,molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, cobaltand mixtures thereof; a graphite metal composite, wherein the metal isan electrically conductive metal selected from the group consisting ofnickel, iron, copper, cobalt, chromium, aluminum, sodium, potassium,iron, copper, tin, titanium, tungsten, zinc, platinum, gold, silver; asulfur composite, wherein the sulfur composite comprises an elementselected from the group consisting of carbon, aluminum, lithium, iron,vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt, sodium, potassium, tin, platinum ormanganese dioxide; and a phosphorus composite, wherein the phosphoruscomposite comprises an element selected from the group consisting ofcarbon, aluminum, lithium, iron, vanadium, titanium, molybdenum, copper,nickel, zinc, tungsten, manganese, chromium, cobalt, sodium, potassium,tin, platinum, or manganese dioxide; and mixtures thereof with at leastone sacrificial template selected from the group consisting of zeolite,MCM-41, silicon dioxide, silicon, copper, copper oxide, nickel, nickeloxide, aluminum, aluminum oxide, tungsten, titanium, titanium nitride,gold, chromium, indium titanium oxide and mixtures thereof to form amixture; subjecting the mixture to ball milling to form a milledmixture; contacting the milled mixture with a chemical etchant selectedfrom the group consisting of acetic acid, phosphoric acid, hydrochloricacid, sulfuric acid, nitric acid, hydrofluoric acid, buffer oxide,potassium hydroxide, sodium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, hydrogen peroxide, ethylenediamine pyrocatechol,water, aqua regia, iodine, potassium iodide and mixtures thereof to forma porous product.

In certain embodiments, the method the step of combining includescombining the material and the sacrificial template with a conductiveadditive selected from the group consisting of activated carbon, Super-Pcarbon and mixtures thereof to form a mixture. In certain embodiments,the method the step of combining includes combining the material and thesacrificial template with a polymer binder selected from the groupconsisting of polyvinylidene fluoride, polytetrafluoroethylene,styrene-butadiene rubber and mixtures thereof to form a mixture. Incertain embodiments, the method also includes the steps of combining theporous product with a solvent selected from the group consisting ofwater, methanol, ethanol, dimethyl sulfoxide, dimethyl formamide,N-methyl pyrrolidone and mixtures thereof and mixing to form a slurry;casting the slurry on a substrate selected from the group consisting ofaluminum, stainless steel, nickel, copper and pyrolytic graphite; anddrying the slurry and the substrate to form an electrode. In certainembodiments, the method also includes the step of contacting theelectrode with an 1-50 wt % aqueous solution of hydrogen peroxide for5-60 minutes at room temperature.

In certain embodiments, a method is disclosed that includes the steps ofcombining Li_(1-x)MnO₂ powder with at least one of deionized water, abase selected from the group consisting of lithium hydroxide, potassiumhydroxide, sodium hydroxide, tetramethyl ammonium hydroxide and mixturesthereof; an acid selected from the group consisting of phosphoric acid,nitric acid, sulfuric acid, sulfurous acid, acetic acid, hydrochloricacid, hydrofluoric acid, a metal selected from the group consisting ofiron, vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten,manganese, chromium, cobalt and mixtures thereof; and carbon to form amixture; sealing the mixture in a hydrothermal pressure chamber; heatingthe hydrothermal pressure chamber to about 90° C. about 900° C.;treating the heated mixture for about 0.5-24 hours; and retrieving thetreated mixture.

In certain embodiments, a method is disclosed that includes the steps ofcombining iron oxide nanoparticles, delithiated manganese oxide,conductive carbon and polyvinylidene fluoride to form a mixture; addingthe mixture to N-methyl pyrrolidone to form a slurry; coating the slurryonto a metal substrate; placing the slurry-coated metal substrate in amagnetic field; and allowing the slurry to dry.

The above described and other features are exemplified by the followingfigures and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages will be apparent fromthe following more particular description of exemplary embodiments ofthe disclosure, as illustrated in the accompanying drawings, in whichlike reference characters refer to the same parts throughout thedifferent views. The drawings are not necessarily to scale, emphasisinstead being placed upon illustrating the principles of the disclosure.

FIG. 1A is a photograph of aluminum foil suitable for use as an anodethat has been treated with a drop of an aqueous solution of lithiumhydroxide; FIG. 1B is a photograph of the piece of the treated aluminumfoil of FIG. 1A showing a change in the appearance of the drop of theaqueous solution of lithium hydroxide; FIG. 1C is a photograph of thepiece of treated aluminum foil of FIG. 1B showing the greyish-whiteappearance of the aluminum foil following the drying of the lithiumhydroxide solution; FIG. 1D is a photograph of the piece of treatedaluminum foil of FIG. 1C showing the effect of placing a drop ofdeionized water on the treated aluminum foil indicating an increase inhydrophilicity of the treated aluminum foil; and FIG. 1E is a photographof a drop of deionized water on untreated aluminum foil for comparisonto FIG. 1D.

FIG. 2 is a schematic diagram of an exploded view of a test battery 100in a coin cell format, showing the positive case 110, a spring 120, afirst spacer 130, the cathode 140, the separator 150, the anode 160, asecond spacer 170 and the negative case 180.

FIG. 3 is an x-ray photoelectron spectroscopy (XPS) profile of carbonsheets following a 100% depth of discharge, showing a strong peakcorresponding to Al 2p transition, associated with the presence ofgibbsite, Al(OH)₃, crystals.

FIG. 4A shows the voltage profile that was produced by applying currentat a current density of 0.1 mA/cm² to a test battery having an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a cathode comprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M aqueous aluminum nitrate electrolyte. FIG. 4B shows the voltageprofile that was produced by applying current at a current density of0.1 mA/cm² to a test battery having an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisinggraphite-graphite oxide, a 25 μm thick polypropylene separator with anaverage pore size of 0.067 μm, and a 0.5 M aqueous aluminum nitrateelectrolyte. The observed average operating voltage is significantlyhigher with the use of acid treated lithium manganese oxide cathodes,possibly owing to the higher activation energy for diffusion andintercalation of ions. Carbon is known to possess a sufficiently lowactivation energy for diffusion and intercalation of metal ions (theintercalation voltage of lithium ions in carbon against a lithium metaloccurs at about 100 mV).

FIG. 5A shows the battery capacity as a function of cycle index of abattery having an anode comprising an aluminum foil treated with LiOH asdescribed in Example 1, a 25 μm thick polypropylene separator with anaverage pore size of 0.067 μm, and a 0.5 M aqueous aluminum nitrateelectrolyte and a graphite-graphite oxide composite cathode. Thecoulombic efficiency was estimated to be close to 100%, indicatingefficient and reversible charge and discharge kinetics. FIG. 5B showsthe battery capacity as a function of cycle index of a battery having ananode comprising an aluminum foil treated with LiOH as described inExample 1, a 25 μm thick polypropylene separator with an average poresize of 0.067 μm, and a 0.5 M aqueous aluminum nitrate electrolyte andan acid treated Li_(1-x)MnO₂ cathode. The reduction in capacity afterover 800 charge/discharge cycles is only about 3% of the originalcapacity.

FIG. 6A shows sequential cyclic voltammetry profiles of a battery havingan anode comprising an aluminum foil treated with LiOH as described inExample 1, a 25 μm thick polypropylene separator with an average poresize of 0.067 μm, and a 0.5 M aqueous aluminum nitrate electrolyte andan acid treated lithium manganese oxide cathode. FIG. 6B showssequential cyclic voltammetry profiles of a battery having an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a 25 μm thick polypropylene separator with an average pore size of 0.067μm, and a 0.5 M aqueous aluminum nitrate electrolyte and agraphite-graphite oxide cathode. The test batteries in the coin cellformat were cycled at various voltage sweep rates between 10 mV/sec and50 mV/sec within a voltage range of 0 V and 1.5 V.

FIG. 7A shows the results of electrochemical impedance spectroscopy(EIS) of a test cell having an anode comprising an aluminum foil treatedwith LiOH as described in Example 1, a 25 μm thick polypropyleneseparator with an average pore size of 0.067 μm, a 0.5 M aqueousaluminum nitrate electrolyte and an acid treated lithium manganese oxidecathode. FIG. 7B shows the results of electrochemical impedancespectroscopy (EIS) of a test cell having an anode comprising an aluminumfoil treated with LiOH as described in Example 1, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M aqueous aluminum nitrate electrolyte and a graphite-graphite oxidecathode. Insets show the Randles equivalent circuit used to fit thespectra.

FIG. 8A is a schematic representation of a prismatic cell 80.

FIG. 8B illustrates the discharge voltage profile of a prismatic cellrated at 1 mAh. The cell had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisingacid-treated lithium manganese oxide, a 25 μm thick polypropyleneseparator with an average pore size of 0.067 μm, a 0.5 M aqueousaluminum nitrate electrolyte and were tested at 10 μA/cm².

FIG. 9A is a schematic representation of a pouch cell 90.

FIG. 9B illustrates the discharge profile of a pouch cell comprising 0.8cm×1 cm electrodes and hydrophilic polypropylene separators. The cellhad an anode comprising an aluminum foil treated with LiOH as describedin Example 1, a cathode comprising acid-treated lithium manganese oxide,a 25 μm thick polypropylene separator with an average pore size of 0.067μm, a 0.5 M aqueous aluminum nitrate electrolyte and were tested atabout 25 μA/cm².

FIG. 9C illustrates the voltage profile of a single interface pouch cellcycled at 20 μA/cm² where the anode comprised phosphate-treated aluminumfoil, the cathode consisted of acid-delithiated manganese dioxide coatedon nickel foil and the separator was a Celgard 3500 polypropylene sheet.The separator thickness was about 25 μn and the average pore size wasabout 67 nm, and the electrolyte was 0.5 M aqueous aluminum nitrate.

FIG. 10 is a block diagram of a system 800 that incorporates the battery810 of the present disclosure, showing a controller 820 that isoperatively connected to battery 810, a source of electrical power 830,a local electrical load 840 and an electrical power distribution grid850.

FIG. 11 compares the discharge and charging properties of two batteriesdiffering in electrolyte composition: one battery having a 0.5 MAl(NO₃)₃ (aq) electrolyte (curve 1) and another battery having a 0.5 MAl(NO₃)₃ and 2 M LiOH (aq) electrolyte (curve 2). Each battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and wastested at current densities of 10 μA/cm².

FIG. 12 illustrates the effect of separator pore size on the averagedischarge potential produced at a given current density, where pentagons(1) represent measurements made on a battery having a polypropyleneseparator with 0.067 μm pores, a triangle (2) represents measurementsmade on a battery having a mixed cellulose ester separator with 0.20 μmpores, a circle (3) represents measurements made on a battery having anylon separator with 0.45 μm pores, squares (4) represent measurementsmade on a battery having a nylon separator with 0.80 μm pores, anddiamonds (5) represent measurements made on a battery having a glassmicrofiber separator with 1.0 μm pores. Each battery was assembled in a2032 coin cell format and had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisingacid-treated lithium manganese oxide, and the electrolyte was an 0.5 Maqueous aluminum nitrate solution. Polypropylene separators (pentagons)were tested at 10 μA/cm² and 20 μA/cm²; mixed cellulose ester separators(triangle) and nylon separators (circle) were tested at 20 μA/cm²; nylonseparators (squares) were tested at 20 μA/cm², 40 μA/cm² and 50 μA/cm²;and glass microfiber separators (diamonds) were tested at 20 μA/cm² and40 μA/cm².

FIG. 13 illustrates the discharge of a battery having a polypropyleneseparator with 0.067 μm pores at a current density of 10 μA/cm². Thebattery was assembled in a 2032 coin cell format and had an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a cathode comprising acid-treated lithium manganese oxide, and theelectrolyte was an 0.5 M aqueous aluminum nitrate solution.

FIG. 14 illustrates the discharge of a battery having a nylon separatorwith 0.80 μm pores at a current densities of 20 μA/cm² (curve 1), 40μA/cm² (curve 2), and 40 μA/cm² (curve 3). The battery was assembled ina 2032 coin cell format and had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisingacid-treated lithium manganese oxide, and the electrolyte was an 0.5 Maqueous aluminum nitrate solution.

FIG. 15 illustrates the discharge of a battery having a glass microfiberseparator with 1.0 μm pores at a current densities of 20 μA/cm²(curve 1) and 40 μA/cm² (curve 2). The battery was assembled in a 2032coin cell format and had an anode comprising an aluminum foil treatedwith LiOH as described in Example 1, a cathode comprising acid-treatedlithium manganese oxide, and the electrolyte was an 0.5 M aqueousaluminum nitrate solution.

FIG. 16 is a photograph of the free-standing, translucent solid polymerelectrolyte measuring about 1 mm in thickness and about 3 cm indiameter.

FIG. 17 illustrates the voltage profile of a battery having asolid-polymer electrolyte, showing a short duration of discharge at 50μA/cm², followed by discharging at 20 μA/cm² and charging at a currentdensity of 20 μA/cm², with an inset of a photograph of solid polymerelectrolytes. The battery was assembled in a 2032 coin cell format andhad an anode comprising an aluminum foil treated with LiOH as describedin Example 1, a cathode comprising acid-treated lithium manganese oxide,a 25 μm thick polypropylene separator with an average pore size of 0.067μm. The surface of the cathode was further treated with 2 M LiOH priorto assembly and testing. The electrolyte was prepared by mixing 6.7weight % poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), 20weight % aluminum nitrate and 10 weight % LiOH in 73.3 weight %deionized water. The solution was then placed inside a furnacemaintained at 120° C. overnight to remove the water content and obtainthe resultant solid polymer electrolyte.

FIG. 18 shows a discharge profile produced by a combination oflow-current and high-current pulses. The battery was assembled in a 2032coin cell format and had an anode comprising an aluminum foil treatedwith LiOH as described in Example 1, a cathode comprising acid-treatedlithium manganese oxide, a 0.5 M aluminum nitrate (aq) electrolyte and a25 μm thick polypropylene separator with an average pore size of 0.067μm. The current densities were switched between 100 A/g (low-currentpulse) and 500 A/g (high-current pulse), where the current is normalizedwith respect to the mass of the cathode.

FIG. 19 shows discharge voltage profiles illustrating that a combinationof hydroxide etching and delithiation of a MnO₂ cathode along withincorporation of LiOH in the electrolyte can produce a two-fold increasein current densities. Curve 1 was obtained from a battery having a 0.1mAh rating discharged for 8 hours at a current density of 10 μA/cm².Curve 2 was obtained from a battery having a 0.1 mAh rating dischargedfor 5 hours at a current density of 20 μA/cm². Each battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M Al(NO₃)₃ and 2 M LiOH (aq) electrolyte.

FIG. 20 shows a discharging voltage profile (curve 1) and a chargingvoltage profile (curve 2) of a battery having a cathode comprising MnO₂synthesized by a combination of acid-based (nitric acid) delithiationfollowed by 2M LiOH treatment of the MnO₂ coated cathode, where thedischarge cut-off (dashed line) has been set at 1 V. The battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M Al(NO₃)₃ (aq) electrolyte.

FIG. 21 shows a discharging voltage profiles of batteries havingdifferent treatments of the delithiated MnO₂ cathode. Curve 1 is thedischarging voltage profile of a battery having a cathode comprisingMnO₂ that was delithiated using nitric acid. Curve 2 is the dischargingvoltage profile of a battery having a cathode comprising MnO₂ that wasdelithiated with electrochemical delithiation. Curve 3 is thedischarging voltage profile of a battery having a cathode comprisingMnO₂ that was delithiated using nitric acid, followed by treatment ofthe cathode with 2M LiOH. Each battery was assembled in a 2032 coin cellformat and had an anode comprising an aluminum foil treated with LiOH asdescribed in Example 1, a cathode comprising acid-treated lithiummanganese oxide, a 25 μm thick polypropylene separator with an averagepore size of 0.067 μm, and a 0.5 M Al(NO₃)₃ (aq) electrolyte.

FIG. 22 illustrates the discharge voltage profile of a battery having acathode with a 100 μm thick layer of porous MnO₂ cathode, a 15 μm thickaluminum foil anode that had been treated with LiOH as described inExample 1, a 25 μm thick polypropylene separator with an average poresize of 0.067 μm, and a current density of about 10 μA/cm². Theelectrolyte was 20 weight % aluminum nitrate and 80 weight % water.

FIG. 23 illustrates the charge voltage profile (curve 1) and thedischarge voltage profile (curve 2) of a MnO₂ cathode with across-sectional thickness of 100 μm, assembled against a 15 μm thickaluminum foil that had been treated with LiOH, with a glass microfiberseparator and a current density of about 10 μA/cm². The cathode wastreated with H₂O₂ and the electrolyte comprised 10 weight % H₂O₂.

FIG. 24 is charge-discharge voltage profile of acid-delithiated,iodine-doped manganese oxide cathode. The battery was assembled in a2032 coin cell format and had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, an acid-delithiated,iodine-doped manganese oxide cathode, a 25 μm thick polypropyleneseparator with an average pore size of 0.067 μm, and a 0.5 M Al(NO₃)₃(aq) electrolyte. Even at about 2-times the discharge current density,the cathode displayed low charge and discharge hysteresis of 84 mV and129 mV respectively.

FIG. 25 is an XPS profile of an aluminum metal foil anode.

FIG. 26 is an XPS profile of a manganese oxide cathode.

FIG. 27 illustrates the charge and discharge cycle of a batterycomprising a titanium oxide cathode, an anode comprising an aluminumfoil treated with LiOH as described in Example 1, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and 0.5 MAl(NO₃)₃ electrolyte.

FIG. 28 illustrates the charge/discharge voltage profile of an aluminumion battery having an organic electrolyte.

FIG. 29 compares the voltage profile of an aluminum ion battery having a0.5 M Al(NO₃)₃ (aq) electrolyte (curve 1, filled triangles) to thevoltage profile of an aluminum ion battery having a 0.5 M Al(NO₃)₃ (aq)electrolyte containing 10% methanol (curve 2, filled circles).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following non-limiting examples further illustrate the variousembodiments described herein.

The aluminum ion battery chemistry described in this disclosure relieson simple electrode and aqueous electrolyte chemistry and is based onthe movement of hydroxyaluminates between an aluminum anode source and ahost cathode material. Incorporation of aluminum anode and graphite oracid-treated lithium manganese oxide cathode, along with an aqueouselectrolyte comprising an inexpensive aluminum salt ensurescost-competitiveness of the technology. Aluminum is abundantly availableand is inherently safer and electrochemically more robust compared tolithium metal, facilitating the use in aqueous environments as well asambient atmospheric conditions in a safe and reliable manner. Moreover,the approach adopted here to incorporate hydrophilicity toaluminum-based anodes is inexpensive and highly scalable. Both carbonand lithium manganese oxide cathodes are easy to manufacture and areconsidered to be extremely safe over a wide range of operatingconditions and are compatible with a wide range of aqueous, non-aqueous,ionic and solid electrolytes, lending flexibility and scalability to thebattery technology. Moreover the use of air stable electrodes andaqueous electrolytes is expected to significantly reduce the time, costand complexity of manufacturing of the proposed aluminum ion aqueousbattery relative to other competing battery chemistries that rely onelaborate manufacturing and assembly techniques, often inhumidity-controlled dry room environments. The preliminary performanceparameters indicate excellent reliability and repeatability. Theestimated volumetric and gravimetric energy density are about 30 Wh/Land 75 Wh/kg respectively for the aluminum-graphite system and 50 Wh/Land 150 Wh/kg respectively for the aluminum-lithium manganese oxidesystem, normalized with respect to the mass and volume of cathode,thereby offering significant advancements over alternate emergingbattery technologies.

As used herein, “aluminum” and “aluminium” are used interchangeably torefer to the same element. “Aluminum” is the preferred term that isused.

As used herein, “aluminum ion” includes aluminum ion, Al³⁺ andpolyatomic aluminum anions, such as the hydroxyaluminate anion, Al(OH)₄¹⁻, the tetrachloroaluminate ion, AlCl₄ ¹⁻, the tetrahydroaluminate ion,AlH₄ ¹⁻, and the hexafluoroaluminate ion, AlF₆ ¹⁻, aluminumtetranitrate, Al(NO₃)₄ ¹⁻, aluminum disulfate, Al(SO₄)₂ ¹⁻,tetrahydroaluminate ion, AlH₄ ¹⁻, tetrafluoroaluminate ion, AlF₄ ¹⁻,tetraboroaluminate, AlBr₄ ¹⁻, tetraiodidealuminate, Al₄ ¹⁻,tetraperchloratealuminate, Al(ClO₄)₄ ¹⁻, tetrahexafluorophosphatealuminate, Al(PF₆)₄ ¹⁻, aluminum dioxide, AlO₂ ¹⁻, tetraborofluoridealuminate, Al(BF₄)₄ ¹⁻ and combinations thereof, wherein the mixtures ofaluminum cations and corresponding negative anions can result in excessnegative charges ranging between −1 and −8, inclusive.

As used herein, “delithiation” or “delithiated” refers to the removal oflithium from lithium manganese oxide, including removal by chemicalmethods, such as acid treatment, and electrochemical methods. Theproduct of the delithiation of lithium manganese oxide can be expressedas Li_(1-x)MnO₂, where x denotes the amount of lithium removed by thedelithiation method. As the delithiation method approaches completeremoval of lithium, x approaches 1, and the product is substantiallyMnO₂. In certain embodiments, the product is substantially MnO₂.

The next generation of energy storage technology should therefore enableelimination of the aforementioned disadvantages while simultaneouslyfacilitating lower costs. A list of the desirable attributes have beenprovided in Table 1, below. In addition, the US Department of Energy hasalso specified four specific challenges to large-scale deployment ofenergy storage for grids: (1) cost-competitive technology, (2) validatedreliability and safety, (3) equitable regulatory environment, and (4)industry acceptance.

TABLE 1 An overview of the desired attributes of next generation batterysystems and their potential impacts Characteristic Impact High operatingvoltages Fewer cells in series; Lower costs of implementation; Abilityto integrate in a wide range of applications including consumerelectronics Characteristic voltage plateau Simplified battery managementsystems Simple electrode and Ease of manufacturing; electrolytecomponents Enhanced safety; Lower cost Room temperature operationImproved safety Minimal external accessories Easy maintenance;(insulation, cooling, pumps, Lower cost storage tanks, etc.)

The aluminum-ion battery storage technology is based on the movement ofaluminum ions between an anode and a cathode, through an aqueouselectrolyte and a separator that is permeable to the aluminum ions. Incertain embodiments, the aluminum ions are polyatomic aluminum anions.In certain embodiments, the separator is a polymeric material. A porous,at least partially hydrophilic polymer separator provides an insulatingseparation layer between the anode and cathode, thereby preventingpotential shorting between the two electrodes. In certain embodiments,the polymer separator is a polypropylene, cellulose ester or nylonseparator. The porosity of the separator is adapted to facilitate themovement of the aluminum ions between the anode and cathode.

Aluminum electrochemistry has several advantages over the other batterytechnologies that are available today. Aluminum has a theoretical energydensity of 1060 Wh/kg, compared to 406 Wh/kg of lithium ions, due to thepresence of three valence electrons in aluminum as compared to onevalence electron in lithium. Aluminum is the third most abundant element(after oxygen and silicon), and the most abundant metal available in theearth's crust (8.1 weight %), compared to lithium (0.0017 weight %),sodium (2.3 weight %) and vanadium (0.019 weight %), providing anopportunity to reduce material costs. Finally, aluminum is bothmechanically and electrochemically robust and can be safely operated inambient air as well as humid environments while simultaneouslyfacilitating a greater flexibility in the choice of electrolytes(aqueous, organic, ionic and solid) and operating conditions.

While aluminum is the preferred element, other electrochemically activeelements that form hydroxides that possess sufficient ionic mobility andelectrical conductivity may also be used. Such elements include alkalimetals such as lithium, sodium and potassium, alkaline earth metals suchas calcium and magnesium, transition metals such as manganese, andpost-transition metals such as tin.

In certain embodiments, the electrolyte comprises an aqueous solution ofan aluminum salt. A preferred solvent is deionized water. In certainembodiments, the aluminum salts include aluminum nitrate, aluminumsulfate, aluminum phosphate, aluminum bromide hexahydrate, aluminumfluoride, aluminum fluoride trihydrate, aluminum iodide hexahydrate,aluminum perchlorate, aluminum hydroxide, and combinations thereof.Preferred aluminum salts are aluminum nitrate, aluminum bromidehexahydrate, aluminum fluoride, aluminum iodide hexahydrate, andcombinations thereof. In an embodiment, the aluminum salt is aluminumnitrate.

In certain embodiments, the aluminum salt is present in an aqueoussolution of about 0.05 M to about 5.0 M. In some embodiments, thealuminum salt is present in an aqueous solution of about 0.5 M to about3.0 M. In certain embodiments, the electrolyte comprises about 0.1M toabout 3.0 M sodium nitrate aqueous solution. In certain preferredembodiments, the electrolyte comprises about 1M to about 3.0 M sodiumnitrate (aqueous).

One of ordinary skill would recognize that the aqueous aluminum saltelectrolyte is environmentally benign, non-toxic and non-flammable andis therefore safer than organic electrolytes used in commercial lithiumion batteries and many sodium ion batteries today.

In certain embodiments, an anode comprises aluminum metal foils. Inpreferred embodiments the aluminum metal foil has been treated toincrease its hydrophilic properties. In other embodiments, an anodecomprises an aluminum compound selected from the group consisting of analuminum transition metal oxide (Al_(x)M_(y)O_(z), where M is atransition metal selected from the group consisting of iron, vanadium,titanium, molybdenum, copper, nickel, zinc, tungsten, manganese,chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive), analuminum transition metal sulfide (Al_(x)M_(y)S_(z), where M is atransition metal selected from the group consisting of iron, vanadium,titanium, molybdenum, copper, nickel, zinc, tungsten, manganese,chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive), analuminum transition metal nitride (Al_(x)M_(y)N_(z), where M is atransition metal selected from the group consisting of iron, vanadium,titanium, molybdenum, copper, nickel, zinc, tungsten, manganese,chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive), analuminum transition metal carbide (Al_(x)M_(y)C_(z), where M is atransition metal selected from the group consisting of iron, vanadium,titanium, molybdenum, copper, nickel, zinc, tungsten, manganese,chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive),aluminum lithium cobalt oxide (AlLi₃CoO₂), lithium aluminum hydride(LiAlH₄), sodium aluminum hydride (NaAlH₄), potassium aluminum fluoride(KAlF₄), aluminum indium oxide, aluminum gallium oxide, aluminum indiumsulfide, aluminum gallium sulfide, aluminum indium nitride, aluminumgallium nitride, and mixtures thereof.

In certain embodiments, an anode comprises an alloy of aluminum and atleast one metal selected from the group consisting of lithium, sodium,potassium, manganese and magnesium. In certain embodiments, the anodecomprises aluminum and at least one of manganese, magnesium, lithium,zirconium, iron, cobalt, tungsten, vanadium, nickel, copper, silicon,chromium, titanium, tin and zinc. The operating voltage in batteriesthat use carbon-based cathodes could be increased through theincorporation of high activation energy alloy anodes.

Improvement of cathode materials can be gained by introduction ofporosity and voids or modifications in the grain structure andorientation within the existing graphite or lithium manganese oxidecompositions. Such improvements can provide a more efficient movementand storage of larger charged ions in the discharge reaction, therebyincreasing the net capacity of the battery.

Alternatives to aluminum anodes, such as aluminum metal sulfides andaluminum metal oxides can potentially offer higher operating voltages,associated with the high activation energy of such compounds. Moreover,such alternatives also facilitate the incorporation of a mixed,hybrid-ion technology whereby the capacity contribution is availablefrom more than one metal ion, thereby directly increasing the achievablecapacities and hence, available energy densities. Such alternatives toaluminum anodes are also more stable over a wider range of operatingparameters such as mechanical stresses, high/low operating temperaturesand choice of electrolytes.

Examples of the chemical reactions associated with aluminum metal oxidesis provided below:Al₂CoO₄→AlCoO₄+Al³⁺+3e  (1)

Where cobalt changes its oxidation state from Co³⁺ to Co⁵⁺ following thedissociation reaction of cobalt aluminate and the release of onealuminum ion.AlLi₃CoO₂→CoO₂+Al³⁺+3Li⁺+6e  (2).

Cobalt changes its oxidation state from Co²⁺ to Co⁴⁺ following thedissociation reaction and the release of one aluminum ion and threelithium ions.

In general, the active ions may come from the electrode comprising ofaluminum alloys or aluminum-based compounds, an electrolyte comprisingof one or more of aluminum salts, salts of one or more of aluminum,carbon, lithium, sodium, potassium, calcium, magnesium, manganese andother active ions such as sulfate, phosphate, nitrate, hydroxide,oxides, carbonates and halides Another example that involvescontribution of active ions from both the anode and electrolyte saltwould be:2Al+4H₂O+AlCl₃+CH₃Cl→Al(OH)₄ ¹⁻+AlCl₄ ¹⁻+4H¹⁺+CH₃ ¹⁺  (3)where the electrolyte comprises water (solvent), methyl chloride (salt)and aluminum chloride (salt) and the anode is aluminum metal.

In embodiments using aluminum compounds comprising alkali metals, thefollowing reactions can be considered.AlH₄ ¹⁻+Na¹⁺→NaH+AlH₃  (4).AlF₆ ³⁻+3Li¹⁺→Li₃F₃AlF₃  (5).

Aqueous electrolytes containing a dispersion of alternate aluminum salts(such as sulfates, phosphates and perchlorates) can effect changes inionic mobility and operating voltages. Electrolytic additives such aslithium chloride and sodium sulfate are being studied to understandtheir effect on operating voltages. Moreover, additional metal saltswill be incorporated into the electrolyte based on the confirmation ofan alternate aluminum-metal alloy anode. Studies are also underway tofurther improve the electrolyte performance through incorporation ofelectrolytic salts or hydrolysis suppressants. Investigation of thesaturation limit of the electrolytic salts could prevent dissolution ofreaction products during charge and discharge, a phenomenon commonlyobserved in lithium sulfur batteries, thereby increasing energy density,Coulombic efficiency and longevity of the battery storage system. On theother hand, hydrolysis suppressants including but not limited tophosphoric acid, phosphorous acid, acetic acid, carboxylic acid, formicacid, formamides, halogenated hydrocarbons, silicone, sulfates,nitrates, halides and phosphates of alkali metals including lithium,sodium, potassium and calcium, bis(trifluoromethane)sulfonamides andbis(fluorosulfonyl)imides of alkali metals including lithium, sodium,potassium and calcium, epoxy, mineral oils, synthetic hydrocarbon oils,esters, aromatic halides, ethers and aromatic ethers can used.

In addition to aqueous electrolytes, ionic liquid electrolytes offer theability to achieve significantly higher operating voltages(typically, >5 V), thereby increasing the achievable energy density(defined as the product of charge storage and operating voltage). Solidelectrolytes, comprising aluminum and aluminum-metal-based saltsdispersed in polymers such as polyethylene oxides will also be tested inthe proposed aluminum ion battery chemistry. Solid electrolytes are lowcost alternatives to ionic electrolytes that allow reasonably highoperating voltages along with a marked improvement in terms of ionicmobility.

In certain embodiments, the separator is a porous polypropyleneseparator or a nylon membrane separator that provides an insulatinglayer between the anode and cathode along and provides sufficientporosity for the efficient transport of ions between the two electrodes.In certain embodiments, the separator comprises a porous polymermaterial selected to provide the needed functionality at lesser expense,which can significantly drive down the cost of the technology.

The onset, extent and impact of electrolysis within the batterychemistry has been studied. The current set of operating parameters relyon relatively low voltages at which electrolysis will be absent or atthe most, inconsequential. However, the choice of electrodes andelectrolytes bring in a sufficient degree of thermodynamic non-idealityfactor which can increase the electrolysis voltage to as much as 1.8 V(instead of 1.23 V). Such high operating voltages with aqueouselectrolytes not only enable higher capacities but can also lead to theintroduction of additional reaction mechanisms which were otherwiseunavailable at voltages less than 1.2 V. In terms of hybrid ion batterychemistries, higher operating voltage can also introduce the involvementof multiple metal ions such as lithium ions from the lithium manganeseoxide cathode. Further studies throughout an entire range of operatingparameters to determine the characteristic responses of the batterytechnology.

Cathode Materials. Two cathode materials were studied in workingexamples: acid or electrochemically treated lithium manganese oxide andgraphite-graphite oxide composite. A suitable cathode material shouldhave sufficient porosity and inter-sheet voids to accommodate theinsertion and intercalation of large polyatomic aluminum anions. Thecathode material should also be at least partially hydrophilic, ortreated to achieve at least partial hydrophilicity, for wettability withan aqueous electrolyte. These two cathode materials meet these criteria,but other materials, notably graphene, polyvinyl alcohol, polyacrylicacid, polymethyl methacrylate, polyvinylpyrrolidone, polyethyleminine,polyethylene glycol, polyethylene oxide, tin oxide, vanadium oxide,titanium oxide, silicon oxide, iron oxide, cobalt oxide, manganesedioxide, molybdenum sulfide, tungsten sulfide, iron phosphate, silicon,molybdenum, tin and germanium could also meet these criteria.

Pristine graphite cathodes do not typically provide large inter-sheetvoids and porosity or hydrophilicity. While oxygen plasma treatedgraphite could improve the hydrophilicity of the cathode material, thereis an issue of whether inter-sheet voids would accommodate largepolyatomic aluminum anions.

The spinel structure of lithium manganese oxide provides hydrophilicityas well as porosity and inter-sheet voids suitable for accommodatinglarge polyatomic aluminum anions. Similarly, graphite-graphite oxidecomposites were found to be suitable cathode materials for the proposedaluminum-ion chemistry, owing to the hydrophilicity and largeinter-sheet voids introduced by the oxygen atoms.

One of ordinary skill would recognize that graphene also hassufficiently large inter-sheet voids, owing to the precursor grapheneoxide material, which is subsequently reduced to increase conductivityand form graphene. However, graphene is inherently hydrophobic andtherefore, graphene sheets need to be exposed to oxygen plasma tointroduce oxygen containing species and improve hydrophilicity.Alternatively, graphene can be mixed with hydrophilic functional groups,such as hydroxyls, carbonyls, carboxyl, aminos, phosphates andsulfhydrils, to introduce partial hydrophilicity. Additional alternatecathode materials capable of accommodating the diffusion and storage oflarge aluminum-based ions, such as tin oxide, vanadium oxide, titaniumoxide, silicon oxide, iron oxide, cobalt oxide, manganese dioxide,molybdenum sulfide, tungsten sulfide, iron phosphate, silicon,molybdenum, tin and germanium, are being studied to evaluate on thecost, porosity and inter-sheet voids of the potential materials.

Lithium manganese oxide materials can be improved by leaching lithiumatoms from the lithium manganese oxide materials through treatment withacids. When the lithium manganese oxide material is treated with amineral acid such as nitric acid or hydrochloride acid, the lithiumatoms are removed in the form of the corresponding lithium nitrates orlithium chlorides, thereby creating additional voids within the cathodestructure. Suitable acids include aqueous solutions of 10%-90% nitric,hydrochloric, sulfuric, acetic, hydroiodic, hydrofluoric, or phosphoricacid. In one embodiment, lithium atoms can be removed by dispersinglithium manganese oxide in an acidic medium (30%-70% concentratedhydrochloric or nitric acids) and sonicated for 1-6 hours until a stabledispersion is obtained. In other embodiments, lithium atoms can beremoved by dispersing lithium manganese oxide in an acidic medium (wherethe pH of the medium is maintained between 0.01 and 7.0) and sonicatedfor 1-24 hours until a stable dispersion is obtained If nitric acid isused the color of the lithium manganese oxide changes from black tobrownish-red. In another embodiment, lithium atoms can be removed bystirring the suspension of dispersing lithium manganese oxide in anacidic medium at room temperature for about 0.5 to about 6 hours,typically about two hours. In another embodiment, lithium atoms can beremoved by stirring the suspension of dispersing lithium manganese oxidein an acidic medium (where the pH of the medium is maintained between0.01 and 7.0) at room temperature for about 1 to about 24 hours,typically about twelve hours. In other embodiments, the suspensions werestirred for various durations from 0.5 hours to 24 hours at differenttemperatures from room temperature to about 80° C. The resultingsuspension is then filtered through a filter membrane with pore sizeranging from 0.1-40 μm, preferably with a pore size greater than 0.2 μmand is repeatedly washed with deionized water or ethanol to remove traceamounts of residues, such as LiNO₃. Suitable filter membrane materials,such as nylon, are those that can withstand the acid used in theprocess. The filtrate is then dried in a vacuum furnace to obtain theresultant powder, Li_(1-x)MnO₂, where x denotes the amount of lithiumremoved by the acid treatment process. As the acid treatment approachescomplete removal of lithium, x approaches 1, and the product issubstantially MnO₂.

In certain embodiments, commercially available lithium manganese oxideis dispersed in 30% concentrated hydrochloric acid or 67% concentratednitric acid and sonicated for six hours until a stable dispersion isobtained. Formation of a dispersion is indicated by a change in colorfrom black to reddish brown. The resulting suspension is then filteredthrough a Whatman nylon membrane filter with pore size ranging from0.2-0.45 μm and is repeatedly washed to remove trace amounts of theacid. The residue is then dried in a vacuum furnace at 110° C. to obtainthe resultant powder, Li_(1-x)MnO₂.

In certain embodiments, acid-delithiated or electrochemicallydelithiated manganese oxide maybe further subjected to a hydrothermalreaction, steam exfoliation or gas-based exfoliation. Hydrothermalreaction involves combining Li_(1-x)MnO₂ powder with one or acombination of deionized water, base (such as KOH), acid (such asH₂SO₄), metals (such as copper) and carbon, sealing the mixture in ahydrothermal pressure chamber and heating the chamber at temperaturesranging from 90° C. to 900° C. for 0.5 hours to 24 hours. The product isthen washed several times in deionized water and ethanol to obtain theporous Li_(1-x)MnO₂. The product may be further subject to wet or dryetching to remove trace contaminants such as metals, oxides, sulfides,sulfates and hydroxides. Steam exfoliation or gas-based exfoliation(where the gas may include one or a combination of and not limited tocarbon dioxide, carbon monoxide, sulfur dioxide, nitrogen dioxide) relyon a flow of steam or gas within a temperature range of 100° C. to 2000°C. and a pressure range of 1 atmospheres to 10 atmospheres to introducestructural expansion in Li_(1-x)MnO₂.

In certain embodiments, lithium manganese oxide, acid-treated lithiummanganese oxide, electrochemically delithiated lithium manganese oxide,lithium metal manganese oxide, acid-treated lithium metal manganeseoxide, transition metal oxide, transition metal sulfide, transitionmetal nitride, transition metal carbide, aluminum transition metaloxide, aluminum transition metal sulfide, aluminum transition metalnitride, aluminum transition metal carbide, graphite metal composite,graphite-graphite oxide, manganese dioxide, electrolytic manganesedioxide, sulfur composites, phosphorus composites, and graphene can befurther mixed with a metal such as copper, nickel, iron, zinc, lithium,sodium, potassium, magnesium, titanium, vanadium, chromium, molybdenum,tungsten, manganese, cobalt, indium, aluminum and lead, a semi-metal ormetalloid such as boron, silicon and germanium, zeolite and oxides,phosphates, phosphides, sulfates, sulfides, nitrates, nitrides,hydroxides and carbonates of metals and metalloids. The metal,semi-metal, zeolite and compounds of the metals and metalloids may besubsequently etched away by a suitable selective dry or wet etchingprocess in order to create a porous structure.

Batteries were fabricated that used the aluminum based electrochemistry,including an aluminum anode and an aqueous solution of an aluminum saltas an electrolyte. In certain embodiments, batteries contained analuminum anode, an acid treated lithium manganese oxide cathode and anaqueous solution of an aluminum salt as an electrolyte in a coin cellconfiguration. In certain embodiments, batteries contained an aluminumanode, a graphite-graphite oxide composite cathode and an aqueoussolution of an aluminum salt as an electrolyte in a coin cellconfiguration. In certain embodiments, batteries contained an aluminumanode, a graphene cathode and an aqueous solution of an aluminum salt asan electrolyte in a coin cell configuration. When a 1 M aqueous solutionof aluminum nitrate was used as the electrolyte, the batteries having analuminum anode and an acid treated lithium manganese oxide cathodechemistry provided an open circuit voltage of about 1 volt. When a 1 Maqueous solution of aluminum nitrate was used as the electrolyte, thebatteries having an aluminum anode and graphite-graphite oxide compositecathode provided an open circuit voltage between 600 mV and 800 mV. Whena 1 M aqueous solution of aluminum nitrate was used as the electrolyte,the batteries having an aluminum anode and a graphene cathode providedan open circuit voltage between 600 mV and 800 mV. When the cells weredischarged, aluminum-based ions migrated from the anode towards thecathode. Following a discharge, when the cells were charged, aluminumions migrated to the anode.

WORKING EXAMPLES Example 1 Alkali Metal Hydroxide Treatment of theAluminum Anode

Battery-grade pristine aluminum foils were treated to increasehydrophilicity and improve wettability of the anode. While not wishingto be bound by theory, it is believed that a hydrophobic aluminum anodewould prevent efficient ion transport due to high interfacial resistancebetween the aluminum metal and aqueous electrolyte interface, leading toa significant drop in performance. The hydrophilicity of the surface ofthe aluminum metal was increased by treatment with a lithium hydroxideaqueous solution. Lithium is known to have a strong affinity foraluminum, forming a range of lithium-aluminum based alloys,characterized by the formation of a greyish-white texture on thealuminum surface. The resulting aluminum anode is found to besignificantly more hydrophilic than untreated, pristine aluminum.Aqueous solutions of other alkali metal hydroxides, such as sodiumhydroxide and potassium hydroxide, are also suitable for use in thistreatment.

FIG. 1A is a photograph of a piece of aluminum foil treated with a dropof 1 M aqueous solution of lithium hydroxide; FIG. 1B is a photograph ofthe piece of the treated aluminum foil of FIG. 1A showing a change inthe appearance of the drop of the aqueous solution of lithium hydroxide.After a short time the aqueous solution of lithium hydroxide was wipedaway and the surface of the aluminum foil was allowed to air dry at roomtemperature (25° C.). Reaction times of 5-10 seconds to 1 hour have beentested, but the reaction appears to be complete in 5-10 seconds. FIG. 1Cis a photograph of the piece of treated aluminum foil of FIG. 1B showingthe greyish-white appearance of the aluminum foil following the dryingof the lithium hydroxide solution. FIG. 1D is a photograph of the pieceof treated aluminum foil of FIG. 1C showing the effect of placing a dropof deionized water on the treated aluminum foil, indicating an increasein hydrophilicity of the treated aluminum foil. FIG. 1E is a photographof a drop of deionized water on untreated aluminum foil for comparisonto FIG. 1D. In certain embodiments, an aqueous solution of about 0.01Mto about 5.5M lithium hydroxide can be used.

Other means of increasing the hydrophilicity of an aluminum metalsurface, such as nitrogen and oxygen plasma and treatment usingacid-based treatments, primarily rely on the introduction of hydrophilicnative aluminum oxide layers on the metal surface. Acid-based treatmentsinvolve complicated chemistry, increasing manufacturing costs, and havesignificant environmental impacts associated with use and disposal.Plasma treatment, on the other hand, is an expensive high voltageprocess, and is unsuitable for large-scale manufacturing.

Example 2 Aluminum Anode Vs. Lithium Manganese Oxide Cathode Battery andAluminum Anode Vs. Graphite-Graphic Oxide Cathode Battery

Batteries were assembled using an aluminum anode, a lithium manganeseoxide cathode and an aqueous solution of aluminum nitrate as theelectrolyte. Studies were conducted using the standard 2032 coin cellform factor, illustrated in FIG. 2 . FIG. 2 is a schematic diagram of anexploded view of a test battery 100 in a coin cell format, showing thepositive case 110, a spring 120, a first spacer 130, a cathode 140, aseparator 150, an anode 160, a second spacer 170 and the negative case180. Prior to assembly of the test battery 100, aliquots of theelectrolyte are placed between the separator 150 and the anode 160, aswell between the separator 150 and the cathode 140. Preferably, thefirst spacer 130, the cathode 140, the separator 150, the anode 160, andthe second spacer 170 are immersed in and equilibrated with theelectrolyte prior to assembly of the test battery.

A battery grade aluminum foil is used as the anode 160. Battery gradefoils are generally >99% pure. The thickness of any battery-grade foilshould be limited, since the thickness directly impacts the volumetricenergy density at the system level, defined as: (Net Available EnergyDensity in Watt-hours/Total volume of the electrode, including thecurrent collector). Thicker current collectors also reduce the maximumnumber of electrodes that can be stacked in a battery pack/module.Ideally, battery-grade current collectors vary between 8-30 μm inthickness. Mechanical robustness is also necessary to prevent any wearand tear during the electrode coating or cell/battery assembly process.The tensile strength of commercial battery-grade foils vary between100-500 N/mm. Suitable battery grade aluminum foil and other materialsmay be obtained from MTI Corporation, Richmond, Calif. and TargrayTechnology International Inc., Laguna Niguel, Calif. Battery gradelithium manganese oxide cathode and graphite may be obtained from MTICorporation, Richmond, Calif. and Sigma Aldrich, St. Louis, Mo. Grapheneand graphite oxide may be purchased from Sigma Aldrich, St. Louis, Mo.,Graphene Supermarket, Calverton, N.Y., and ACS Material, Medford, Mass.

Aluminum foil anodes were treated as described in Example 1 to improvetheir hydrophilic properties.

The charge/discharge steps were carried out in the voltage window of0-2V. As the cell was discharged, hydroxyaluminate (Al(OH)₄ ⁻) ions wereformed according to chemical reaction (6):Al³++4OH⁻→Al(OH)₄ ⁻  (6).

The hydroxyaluminate ions migrate towards the cathode, passing throughthe porous membrane separator.

At the cathode, the hydroxyaluminate ions diffuse through the pores andinter-sheet voids of the cathode material and are oxidized to giveAl(OH)₃ (aluminum hydroxide). The presence of aluminum hydroxide on thealuminum foil anode of a completely (100%) discharged test cell has beenconfirmed using x-ray photoelectron spectroscopy (XPS), as shown in FIG.3 . The XPS profile shows one major Al 2p transition at 74.3 eV,indicating the presence of gibbsite, Al(OH)₃ on the anode. Thetransition at 74.3 eV has been reported to be characteristic of gibbsiteby Kloprogge et al. Kloprogge, J. T., et al., XPS study of the majorminerals in bauxite: gibbsite, bayerite and (pseudo-) boehmite, Journalof Colloid and Interface Science, 2006, 296(2), 572-576. In the reversecharging process, aluminum hydroxide is reduced at the cathode and thealuminum ions migrate back to the anode.

The discharge and charge reactions at the cathode, chemical reactions(7) and (8), respectively, are provided below:Discharge, Al(OH)₄ ⁻→Al(OH)₃+OH⁻+3e  (7);Charge, Al(OH)₃+3e ⁻→Al³⁺+3OH⁻  (8).

During the charging process, an additional contribution may be observedat the acid treated lithium manganese oxide cathode through thedissociation reaction of lithium manganese oxide according to reaction(9), below:LiMnO₂ +e ⁻→Li⁺+MnO₂  (9).

The lithium ions would then flow towards the aluminum anode and possiblyintercalate with aluminum, owing to the high affinity between lithiumand aluminum, forming a hybrid-ion battery chemistry. This hypothesiscould relate to an observed increase in capacity (about 40%) compared tothe capacities obtained with carbon-based cathodes devoid of any lithiumcomponent. However, XPS examination of the aluminum anode in a test cellhaving a lithium manganese oxide cathode did not show any significantsigns of lithium-based alloys at the anode site at a fully chargedstate. However, this result can be attributed to the fact that thedissociation reaction of lithium manganese oxide occurs at significantlyhigher voltages (>3V) and in the given voltage window, the concentrationof lithium ions is negligible compared to the presence of aluminum-basedalloys. In addition, XPS is a surface-based analytic technique and theexcellent lithium ion diffusion in aluminum might have caused thelithium ions to have diffused within the bull aluminum anode and wouldtherefore be absent from the surface.

Operating Parameters and Performance Metrics. The aluminum-ion cellswere cycled between safe voltage cut-off limits of 0 V (discharge) and 2V (charge). However, the average operating voltage was about 1.1 V fordischarge and 1.2 V for charge for the cells having an aluminum anodeand an acid treated lithium manganese oxide cathode (FIG. 4A) and 0.4 Vfor discharge and 0.9 V for charge for the cells having an aluminumanode and a graphite-graphite oxide cathode (FIG. 4B), within the safevoltage cut-off limits.

FIG. 4A shows the voltage profile that was produced by applying currentat a current density of 0.1 mA/cm² to a test battery having an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a cathode comprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M aqueous aluminum nitrate electrolyte. FIG. 4B shows the voltageprofile that was produced by applying current at a current density of0.1 mA/cm² to a test battery having an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisinggraphite-graphite oxide, a 25 μm thick polypropylene separator with anaverage pore size of 0.067 μm, and a 0.5 M aqueous aluminum nitrateelectrolyte. The observed average operating voltage is significantlyhigher with the use of acid treated lithium manganese oxide cathodes,possibly owing to the higher activation energy for diffusion andintercalation of ions. Carbon is known to possess a sufficiently lowactivation energy for diffusion and intercalation of metal ions (theintercalation voltage of lithium ions in carbon against a lithium metaloccurs at about 100 mV).

Moreover, the voltage profile demonstrates a characteristic voltageplateau (FIG. 4A), unlike the voltage profiles observed in sodium ionbatteries, enabling critical advantages such as incorporation of simplerbattery management systems and installation of fewer cells in seriesowing to the high operating voltages, all of which can significantlydrive down the cost of the technology. The charge/discharge rates werelimited between C/1 and C/12 (a rate of C/n implies charge or dischargein n hours). While cycle life testing is currently underway, both thegraphite-based and lithium manganese oxide-based configurations have sofar demonstrated impressive cycle life, delivering close to about 100%coulombic efficiency (defined as the ratio of charge to dischargecapacities and is indicative of irreversibility and side-reactions in abattery chemistry). FIG. 5A shows the battery charge capacity, opentriangles, and discharge capacity, open circles, as a function of thecycle index of a battery having an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a 25 μm thick polypropyleneseparator with an average pore size of 0.067 μm, and a 0.5 M aqueousaluminum nitrate electrolyte and a graphite-graphite oxide compositecathode. The coulombic efficiency was estimated to be close to 100% over30 charge/discharge cycles, indicating efficient and reversible chargeand discharge kinetics.

FIG. 5B shows the battery charge capacity as a function of cycle indexof a battery having an anode comprising an aluminum foil treated withLiOH as described in Example 1, a 25 μm thick polypropylene separatorwith an average pore size of 0.067 μm, and a 0.5 M aqueous aluminumnitrate electrolyte and an acid treated Li_(1-x)MnO₂ cathode. Thereduction in capacity after over 800 charge/discharge cycles is about 3%of the original capacity.

Understandably, the acid treated lithium manganese oxide-aluminumchemistry with an aqueous electrolyte provides higher energy density(about 100-150 Wh/kg) and volumetric energy density (about 30-60 Wh/L)than the graphite-graphite oxide-aluminum chemistry (about 50-75 Wh/kgand about 20-30 Wh/L), owing to the higher electrochemical affinitytowards aluminum observed in acid treated lithium manganese oxide.However, graphite-graphite oxide cathodes are generally cheaper thanlithium manganese oxide. Further modifications to the cathode chemistrymay significantly boost the performance metrics of graphite-graphiteoxide cathodes.

Sequential cyclic voltammetry tests were carried out to measure the iondiffusion coefficient in batteries having aluminum anodes and acidtreated lithium manganese oxide cathodes (FIG. 6A) or batteries havingaluminum anodes and graphite-graphite oxide composite cathodes (FIG.6B). The test batteries in the coin cell format were cycled at variousvoltage sweep rates between 10 mV/sec and 50 mV/sec within a voltagerange of 0 V and 1.5 V.

The diffusion coefficient was calculated using Fick's law followingequation (I):

$\begin{matrix}{\frac{\partial C}{\partial t} = {{D\frac{\partial^{2}C}{\partial r^{2}}} + {\frac{2D}{r} \cdot {\frac{\partial C}{\partial r}.}}}} & (I)\end{matrix}$

The response of current can then be obtained as:

$\begin{matrix}{i = {\frac{nFADC}{R_{0}} + {\frac{{nFAD}^{1/2}C}{\pi^{1/2}t^{1/2}}.}}} & ({II})\end{matrix}$

Where n is the number of electrons exchanged, F is Faraday's constant, Ais the area of the electrode, D is the diffusion coefficient, C is themolar concentration, t is time for diffusion and R₀ is the radius of thecathode particles.

The current response can be simplified and re-written as:i=kt ^(1/2) +b  (III),

where

$\begin{matrix}{{b = \frac{nFADC}{R_{0}}},} & \left( {{IV},V} \right) \\{{k = {\frac{{nFAD}^{1/2}C}{\pi^{1/2}}\mspace{14mu}{or}}},} & \; \\{D = {\frac{b^{2}R_{0}^{2}}{\pi\; k^{2}}.}} & ({VI})\end{matrix}$

Subsequently, the diffusion coefficient of hydroxyaluminate ions inlithium manganese oxide and graphite-graphite oxide composite cathodeswas calculated to be 1.14×10⁻⁷ cm²/sec and 3.54×10⁻⁸ cm²/secrespectively, well within the acceptable range of ion diffusioncoefficients in metal-ion batteries.

In addition, electrochemical impedance spectroscopy (EIS) was carriedout to analyze the internal resistances of batteries having an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a 25 μm thick polypropylene separator with an average pore size of 0.067μm, and a 0.5 M aqueous aluminum nitrate electrolyte and an acid treatedlithium manganese oxide cathode (FIG. 7A) and batteries having an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a 25 μm thick polypropylene separator with an average pore size of 0.067μm, and a 0.5 M aqueous aluminum nitrate electrolyte and agraphite-graphite oxide cathode (FIG. 7B). Insets show the Randlesequivalent circuit used to fit the spectra.

Since the operating voltages are close to the electrolysis voltage ofthe aqueous electrolyte system, analyzing EIS is critical to understandpotential safety threats associated with gas evolution inside the cell.It is understood that the evolution and presence of gas pockets (H₂ andO₂) within the electrolyte will directly increase the electrolyticresistance while the evolution of these gases at theelectrode-electrolyte interface will increase the interfacialresistance.

The EIS profile was fitted with a Randles equivalent circuit model andthe electrolytic resistance, interfacial resistance and charge transferresistances, summarized in Table 2, below, were estimated based on thefit. The electrolytic resistances were estimated to be between 2-4Ω,significantly lower than the typical electrolytic resistances of 10-20Ω,consistent with the absence of any gas pockets within the electrolyte.The interfacial resistance was estimated to be 11Ω at the lithiummanganese oxide-electrolyte interface and 20Ω at the graphite-graphiteoxide-electrolyte interface, again consistent with the absence of anyinsulating gas pockets. The charge transfer resistance of acid treatedlithium manganese oxide was estimated to be about 100Ω while that ofgraphite-graphite oxide composite was estimated to be slightly higher atabout 131Ω, possibly attributed to the presence of oxygen-containingfunctional groups. Charge transfer resistance is indicative of theelectron conductivity of the active electrode material and isindependent of the formation of gas pockets. One of ordinary skill wouldrecognize that a charge-transfer resistance of 100-150Ω is generallyconsidered to be suitable for battery storage applications.

TABLE 2 EIS Profile Results Lithium Manganese Oxide Graphite-GraphiteOxide Parameter Cathode Cathode Rel 2-4 Ω 2-4 Ω Rint 11 Ω 20 Ω Rct about100 Ω about 131 Ω

In order to assess form factor scalability of the aluminum ion batterychemistry, pouch cell and prismatic cells were also assembled andtested. A schematic depiction of the prismatic cell assembly is providedin FIG. 8A. The prismatic assembly 80 comprised a metallic or a polymerbase plate 82 an insulating polymer gasket 84 and a top plate resemblingthe structure of the base plate, not shown for clarity. The componentshad threaded through-holes along its edges. For metallic base and topplates, nylon screws were used to seal the assembly while simultaneouslypreventing a shorting between the two plates while for polymer base andtop plates, both nylon and metallic screws sufficed. A prismatic cellwas assembled with an electrode area of 2 cm×5 cm and rated at acapacity of 1 mAh. Standard polypropylene separators were used in theassembly. The cell comprised a single interface, although multipleinterfaces can also be incorporated with the setup.

FIG. 8B illustrates the discharge voltage profile of a prismatic cellrated at 1 mAh. The cell had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisingacid-treated lithium manganese oxide, a 25 μm thick polypropyleneseparator with an average pore size of 0.067 μm, a 0.5 M aqueousaluminum nitrate electrolyte and were tested at 10 μA/cm².

Pouch cells were assembled by introducing the anode-separator-cathodeinterface in the cell assembly section of an aluminum laminate pouchcell packaging case. This was followed by connecting the electrodes toan aluminum current collector tab through mechanical contacts orultrasonic welding. Next, three edges of the pouch cell were sealedusing a heat sealer set between about 20-50 psi and 150-180° C. Asection of the pouch cell was retained at one of the edges that acted asthe gas trap. The purpose of the gas trap is to contain the gasevolution during the formation cycle, after which the gas trap sectioncan be cut and the edge resealed for subsequent cycling. Prior tosealing the fourth and final edge of the pouch cell, theelectrodes-separator assembly was wetted with the electrolyte. Thefourth edge is sealed in a vacuum sealing furnace with the vacuum set atabout −90 psi. The pressure and temperature parameters are unchanged andare set between 20-50 psi and 150-180° C. respectively. A schematicdiagram of a pouch cell 90 is provided in FIG. 9A, showing a cellassembly section 92, a gas trap 94 and current collector terminals 96. Apouch cell assembled in this fashion involved electrodes between 1cm×0.8 cm and 1 cm×1 cm, rated between 0.06-0.08 mAh.

FIG. 9B illustrates the discharge profile of a pouch cell comprising 0.8cm×1 cm electrodes and hydrophilic polypropylene separators. The cellhad an anode comprising an aluminum foil treated with LiOH as describedin Example 1, a cathode comprising acid-treated lithium manganese oxide,a 25 μm thick polypropylene separator with an average pore size of 0.067μm, a 0.5 M aqueous aluminum nitrate electrolyte and were tested atabout 25 μA/cm². Like the prismatic cell format, a pouch cell assembledin this fashion can also incorporate scalability and multiple interfacescan be packed in series/parallel configurations to achieve apre-determined capacity and voltage rating.

Form factor scalability studies, including assessment of safety,formation cycle and swelling, were carried out through pouch cell tests.Pouch cells having one to four interfaces (where an interface is definedas a unit cell consisting of an anode, a separator and a cathode) wereassembled, sealed and tested at current densities ranging between 5μA/cm² and 20 μA/cm². The anode comprised phosphate-treated aluminumfoil, the cathode consisted of acid-delithiated manganese dioxide coatedon nickel foil and the separator was a Celgard 3500 polypropylene sheet.The separator thickness was about 25 n and the average pore size wasabout 67 nm, and the electrolyte was 0.5 M aqueous aluminum nitrate. Inpreferred embodiments, the phosphate treatment of the aluminum anode wascarried out by immersing pristine aluminum foil in a solution of about0.1-1 M phosphoric acid, with the addition of about 0.1-20 weight %sodium nitrite as an oxidizing agent. The pH was maintained between 1and 4. The reaction time was between about 1-60 minutes at 20-60 degreesCelsius. In order to maintain stacking pressure, the pouch cells wereplaced between adjustable clamps prior to cycling. The cells were thencharged and discharged within a voltage window of 0.75 V and 1.7 V (FIG.9C). The cells displayed an average gravimetric capacity ranging between˜40 mAh/gcathode (when tested at 20 μA/cm²) and ˜70 mAh/gcathode (whentested at 5 μA/cm²).

The need to find an alternate energy storage system to meet theever-increasing demands from various sectors such as consumerelectronics, military, automotive and grid storage have continued torise exponentially in the last decade. While lithium ion batteries areubiquitous today in consumer electronics, its limitations with respectto high costs and potentially hazardous safety threats have limited itsentry in emerging fields such as grid storage, and automotiveapplications. Sodium ion batteries on the other hand may offer amarginal reduction in the cost at the system level but are significantlylimited in performance metrics in terms of available capacities andenergy density, voltage window and the choice of electrolytes. Alternateupcoming technologies such as flow batteries and liquid metal batteriesare still in early stages of development. Moreover, such technologiespose additional challenges in terms of cost of implementation andsafety. For instance, the availability of unlimited capacity in vanadiumredox flow batteries rely on large storage tanks and industrial pumpsthat add to the cost and maintenance of the battery system. Liquid metalbatteries operate at very high temperatures and incorporate the use oftoxic materials such as antimony and lead as well as flammable lithiummetal, thereby posing serious safety concerns.

Also disclosed are systems and methods of using the disclosedrechargeable battery. FIG. 8 is a block diagram of an embodiment of asystem 800 that incorporates the battery 810 of the present disclosure,showing a controller 820 that is operatively connected to battery 810, asource of electrical power 830, a local electrical load 840 and anelectrical power distribution grid 850. In certain embodiments, thesource of electrical power 830 is based on a renewable energy source,that is, a wind turbine or a solar panel. The controller 820 isoperatively connected to the source of electrical power 830 and to thebattery 810 of the present disclosure to mediate the charging of thebattery 810. The controller 820 is operatively connected to the sourceof at least one local electrical loads 840 and to the battery 810 of thepresent disclosure to mediate the discharging of the battery 810. Thelocal electrical loads 840 can include devices requiring DC electricalsupply or AC electrical supply, including, without limitation, cellphone or computer battery chargers, computers, home appliances, waterpumps, and refrigeration equipment. In certain embodiments, thecontroller 820 is operatively connected to a power distribution grid 850to permit selling excess electrical power to the power distribution grid850.

Example 3 Electrolyte Additives

In some examples, the electrolyte, 0.5 M aqueous Al(NO₃)₃, was mixedwith 10-50 vol. % 2 M aqueous LiOH to obtain a composite electrolyte.While not wishing to be bound by theory, it is believed that addition ofLiOH to the electrolyte comprising aluminum ions increases theconcentration of OH⁻¹ in the electrolyte, and therefore prevents loss ofactive ions during transportation through undesired side reactions.Owing to the reactivity of aluminum in water, it is not uncommon toobserve oxidation of Al(OH)₄ ¹⁻ ions prior to reaction at the cathodesite.

The oxidation reaction can be summarized as:Al(OH)₄ ¹⁻→Al³⁺+4OH⁻¹  (10).

Depending on the concentration of OH⁻¹ ions in the electrolyte, therecan be a reduction of active hydroxyaluminate ions reaching the cathode,through a dissociation reaction that subsequently leads to the oxidationof hydroxyaluminate and re-formation of multivalent aluminum ions.Increasing the concentration of OH⁻¹ ions through incorporation of 2 MLiOH in the electrolyte would shift the equilibration of the reaction tofavor Al(OH)₄ ¹⁻ ions over the dissociation to Al³⁺+4OH⁻¹.

FIG. 11 compares the discharge and charging properties of two batteriesdiffering in electrolyte composition: one battery having a 0.5 MAl(NO₃)₃ (aq) electrolyte (curve 1) and another battery having a 0.5 MAl(NO₃)₃ and 2 M LiOH (aq) electrolyte (curve 2). Each battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and wastested at current densities of 10 μA/cm².

The results illustrated in FIG. 11 suggest that incorporation of acomposite electrolyte can result in a reduced over-potential.Incorporation of LiOH in the electrolyte reduces the over-potential bypreventing loss of active Al-ion species during transportation in theelectrolyte. The over-potential relates to the discharge voltagehysteresis caused by the cell composition. The voltage hysteresis duringdischarge is defined as the change from the expected operating voltageattributed to internal cell resistances and is conveyed through theequation ΔV=IR (where, ΔV is the change in voltage, I is the current andR is the internal resistance). The new operating voltage, Vop′, is thendefined as Vop′=Vop−ΔV. In FIG. 11 , curve 1, in which the electrolyteis 0.5 M (aq) Al(NO₃)₃ with no LiOH additive, the higher internalresistances cause an increase in the ΔV value (which is known as theover-potential), causing it to discharge at a lower voltage. Incontrast, the battery having an electrolyte that is 0.5 M Al(NO₃)₃ and 2M LiOH aqueous solution (curve 2) has a reduced internal cellresistance, therefore causing the ΔV value to be less than that of thebattery of curve 1, resulting in a higher discharge potential (whichimplies higher energy density, since energy density=capacity×operatingvoltage).

While the example describes a LiOH—Al(NO₃)₃ composite electrolyte, otherhydroxide-containing compounds may also be introduced into theelectrolyte to achieve similar effects. Some alternate electrolyticadditives include hydroxides of sodium, potassium, ammonium, calcium andmagnesium. Since the alkali metal ion (Li+, Na+ or K+ for example) ispresent only in the electrolyte and has a polarity opposite to Al(OH)₄¹⁻ ions, it will not contribute to discharge capacities.

Example 4 Separators

The aluminum ion chemistry disclosed herein involves the transport oflarge Al(OH)₄ ¹⁻ ions. Therefore, the pore size of the separator candictate the ion transportation kinetics. Standard batteries such aslithium ion batteries generally use a polypropylene separator with poresizes less than 0.1 μm, which is sufficient to permit the flow of therelatively smaller lithium ions. However, as the size of the ionsincrease, as is the case with Al(OH)₄ ¹⁻, small pore sizes hinder theefficient flow of ions, resulting in an increased internal cellresistance and lower charging rate and discharging rate. Therefore, inan effort to reduce accumulation of charge and resistance build-up atthe separator surface, batteries having separators with larger porediameters were studied.

The separators that were tested included polypropylene separators(standard, 0.067 μm pore size; Celgard LLC, Charlotte, N.C.), mixedcellulose ester separators (0.2 μm pore size, Whatman), nylon separators(0.45 μm, 0.8 μm, 1.2 μm pore sizes, Whatman), and glass microfiberseparators (1 μm pore size, Whatman). In general, larger pore sizes,including 0.8 μm and 1.2 μm, permitted faster ion-transfer kinetics andbetter rate capabilities compared to the smaller pore sizes. However asthe pore sizes were further increased, it appeared that there was anincrease in shorting of the anode and cathode that was noticeable at apore diameter of 2.7 μm.

FIG. 12 illustrates the effect of separator pore size on the averagedischarge potential produced at a given current density, where pentagons(1) represent measurements made on a battery having a polypropyleneseparator with 0.067 μm pores, a triangle (2) represents measurementsmade on a battery having a mixed cellulose ester separator with 0.20 μmpores, a circle (3) represents measurements made on a battery having anylon separator with 0.45 μm pores, squares (4) represent measurementsmade on a battery having a nylon separator with 0.80 μm pores, anddiamonds (5) represent measurements made on a battery having a glassmicrofiber separator with 1.0 μm pores. Each battery was assembled in a2032 coin cell format and had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisingacid-treated lithium manganese oxide, and the electrolyte was an 0.5 Maqueous aluminum nitrate solution. Polypropylene separators (pentagons)were tested at 10 μA/cm² and 20 μA/cm²; mixed cellulose ester separators(triangle) and nylon separators (circle) were tested at 20 μA/cm²; nylonseparators (squares) were tested at 20 μA/cm², 40 μA/cm² and 50 μA/cm²;and glass microfiber separators (diamonds) were tested at 20 μA/cm² and40 μA/cm².

The pore size of the separators can also influence suitability of abattery for an intended application. Understandably, separators withlarger pore sizes are also thicker than those with smaller pore sizes.Therefore, while the range of optimum pore sizes is rather large, aspecific choice can be made based on the intended application. Forexample, smaller pore sizes (example, polypropylene, 0.067 μm porediameter and 25 μm thick) can optimize energy density (volumetric andgravimetric) while larger pore sizes (example, glass microfiber, 1 μmpore diameter and 500 μm thick) can optimize rate capability and hence,improve the power density of such batteries.

FIG. 13 illustrates the discharge of a battery having a polypropyleneseparator with 0.067 μm pores at a current density of 10 μA/cm². Thebattery was assembled in a 2032 coin cell format and had an anodecomprising an aluminum foil treated with LiOH as described in Example 1,a cathode comprising acid-treated lithium manganese oxide, and theelectrolyte was an 0.5 M aqueous aluminum nitrate solution.

FIG. 14 illustrates the discharge of a battery having a nylon separatorwith 0.80 μm pores at a current densities of 20 μA/cm² (curve 1), 40μA/cm² (curve 2), and 40 μA/cm² (curve 3). The battery was assembled ina 2032 coin cell format and had an anode comprising an aluminum foiltreated with LiOH as described in Example 1, a cathode comprisingacid-treated lithium manganese oxide, and the electrolyte was an 0.5 Maqueous aluminum nitrate solution.

FIG. 15 illustrates the discharge of a battery having a glass microfiberseparator with 1.0 μm pores at a current densities of 20 μA/cm²(curve 1) and 40 μA/cm² (curve 2). The battery was assembled in a 2032coin cell format and had an anode comprising an aluminum foil treatedwith LiOH as described in Example 1, a cathode comprising acid-treatedlithium manganese oxide, and the electrolyte was an 0.5 M aqueousaluminum nitrate solution.

In addition, as a result of lowered internal resistance, separators withlarger pore sizes enabled a higher voltage of operation, even atsignificantly higher current densities. For example, at a currentdensity of about 20 μA/cm², a polypropylene separator (0.067 μm poresize), a nylon separator (0.8 μm pore size) and a glass microfiberseparator (1 μm pore size) displayed an average discharge potential of1.01 V, 1.17 V and 1.18 V respectively. See FIG. 12 . Table 3, below,summarizes the average charge and discharge potential and the typicalcharge and discharge voltage hysteresis values for batteries constructedwith various separators, compared against baseline (standard 0.067 μmpore size polypropylene separator tested at a current density of about10 μA/cm²).

TABLE 3 Charge & Discharge Characteristics For Specific CurrentDensities And Separators Current Average Average Charge DensityDischarge Discharge Charge Hyster- (μA/ Voltage Hysteresis Voltage esisSeparator cm²) (V) (ΔV, mV) (V) (ΔV) Polypropylene 10 1.11 30 1.20 40(0.067 μm) Mixed cellulose 20 1.11 40 1.26 50 ester (0.2 μm) Nylon (0.45μm) 20 1.12 60 1.33 100 Nylon (0.8 μm) 20 1.17 53 1.34 72 40 1.03 991.40 221 Glass Micro- 20 1.18 47 1.38 64 fiber (1 μm) 40 1.09 72 1.39109 Cotton 60 1.11 3 1.39 0.5

Table 3 shows that batteries having nylon or glass microfiber separatorsproduced higher voltages (1.17 V-1.18 V) compared to standardpolypropylene separators (1.11 V) even at twice the current density. Infurther studies, the discharge and charge hysteresis voltages (voltagedifference between end-of-charge and start-of-discharge andend-of-discharge and start-of-charge respectively) were found to bewithin sufficiently acceptable values even at four-fold higher currentdensities (data not shown).

Other suitable separators also include, but are not limited to,polyvinylidene fluoride, polytetrafluoroethylene, cellulose acetate,nitrocellulose, polysulfone, polyether sulfone, polyacrylonitrile,polyamide, polyimide, polyethylene, polyvinylchloride, cellulose,polyester, rubber, polyolefins, glass mat, polypropylene, mixedcellulose ester, nylon, glass microfiber, polycarbonate, polysulfones,cotton and methacrylates. In addition, anion exchange membranes andproton exchange membranes such as NAFION® may be used as the separator.Ceramic separators including, but not limited to, alumina, zirconiumoxides and silicon oxides can also be used. As identified through thetests, the separators can have a pore size ranging between 0.067 μm and1.2 μm. However, separators with lower or higher porosities andthicknesses can also be used for specific applications.

Example 5 Solid Polymer Electrolytes

In addition to the aqueous electrolyte, a solid polymer electrolyte(SPE) incorporating at least one of aluminum salts with or without atleast one of hydroxides can be used in certain embodiments. Not onlydoes the use of SPEs allow higher operating voltages, it enables astable reaction dynamic over a wide range of operating conditions(temperature, humidity, mechanical stresses, etc.). While the aluminumsalt ensures efficient flow of aluminum ions through the electrolyte,added hydroxides contribute OH⁻ to enable the formation of Al(OH)₄ ¹⁻ions during the transportation of ions. Aluminum salts include but arenot limited to Al(NO₃)₃, Al₂(SO₄)₃ and AlCl₃ and combinations andvariations thereof. Hydroxides include but are not limited to Al(OH)₃,LiOH, NaOH, KOH, Ca(OH)₃, Mg(OH)₂ and NH₄OH and mixtures thereof.

Aluminum Salt-Based SPEs: In a certain embodiment, a cross-linkingpolymer such as poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF:HFP) or polymethyl methacrylate (PMMA) is mixed with aluminumnitrate in a ratio ranging between 1:1 and 1:10. The mixture is thendissolved in a solvent such as N-methyl pyrrolidone or dimethylsulfoxide and heated at temperatures ranging from 50-200° C. underconstant stirring for 2 hours in order to initiate the polymerizationreaction. The solution is observed to turn viscous, following which itis transferred to a vacuum furnace chamber where it is further heated atthe above temperature range for 2-24 hours in order to remove thesolvent and obtain the resultant solid polymer electrolyte. The producedsolid polymer electrolyte comprises the aluminum salt and thecross-linking polymer in the weight ratio that was selected, typicallythe cross-linking polymer at 9-50 wt % and the aluminum salt at 50-91 wt%).

In another embodiment, the cross-linking polymer may be mixed withaluminum halides (such as AlCl₃, AlBr₃, AlI₃) and1-ethyl-3-methylimidazolium chloride (EMIMCl, Sigma-Aldrich),1-ethyl-3-methylimidazolium bromide (EMIMBr, Sigma-Aldrich), or1-ethyl-3-methylimidazolium iodide (EMIMI, Sigma-Aldrich), where theratio of the aluminum halide to the 1-ethyl-3-methylimidazolium halideranges from 1:1 to 5:1 (weight:weight). The combined aluminum halide and1-ethyl methylimidazolium halide is then mixed with the cross linkingpolymer such as PVDF:HFP or PMMA in a ratio of 1:1 to 10:1(weight:weight). Typically, 0.1 to 1 g of the mixture per mL of solventis combined with a solvent such as solvent can be N-methyl pyrrolidoneor DMSO. The mixing and heating steps are similar to the processdescribed above. The resultant solid polymer electrolyte will containaluminum salt, ethyl methylimidazolium halide and the cross-linkingpolymer in the weight ratio that was chosen, typically the cross-linkingpolymer at 9-50 wt % and the aluminum salt at 50-91 wt %.

The mixture dissolved in the solvent is heated between about 50° C. and200° C. for 2-24 hours under constant stirring. In one example, themixture was heated at 90° C. continuously for 2 hours under constantstirring. This step initiates the polymerization reaction. At the end ofthis step, the solution turns viscous indicating successful completionof the polymerization reaction. The mixture is then poured into a flatglass petri dish or other suitable container and transferred to a vacuumfurnace where it is heated between 50° C. and 200° C. overnight or foras long as necessary to completely remove the solvent. At the end ofthis step, a free-standing SPE is obtained that can be released from theglass surface either mechanically (peeling off) or through theapplication of ethanol. A photograph of a SPE is shown in FIG. 16 ,which shows the cylindrical, free-standing, translucent solid polymerelectrolyte that is about 1 mm thick and about 3 cm in diameter.

Introduction of Hydroxides in SPEs: The addition of hydroxides to theelectrolyte, described in Example 3, above, can be achieved byintroducing a suitable hydroxide in the mixture in addition to thecross-linking polymer and aluminum salt. In one embodiment, 100 mglithium hydroxide and 900 mg aluminum nitrate were added to about 5 mLdeionized water which resulted in the formation of aluminum hydroxide bythe following reaction:3LiOH+Al(NO₃)₃→Al(OH)₃+3LiNO₃  (11).

In a separate container, poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP, Sigma-Aldrich) was dissolvedin acetone, at a concentration of 500 mg of the polymer in 5 mL acetone,through bath sonication for up to 6 hours, while the bath itself wasmaintained at a temperature of 60° C. The volume of acetone wasmaintained at 5 mL through subsequent addition of the solvent as andwhen required. Upon dissolution of PVDF-HFP in acetone, 5 mL of thesolution was added to 5 mL of the aqueous electrolyte solutioncomprising the reaction products of lithium hydroxide and aluminumnitrate dispersed in DI water. The addition of the PVDF-HFP solution tothe aqueous electrolyte solution initiated a polymerization reactionwhich resulted in the formation of a free-standing solid polymerelectrolyte as shown in the inset of FIG. 17 .

In a particular embodiment, a solid polymer electrolyte prepared by themethod described in the above paragraph was tested in a 2032 coin cellcomprising of a cathode comprising manganese oxide treated by acid-baseddelithiation followed by lithium hydroxide etching of the cathode, andan anode comprising aluminum foil treated as described in Example 1. Noseparators or liquid electrolytes were used and the solid polymerelectrolyte was sandwiched between the anode and cathode.

FIG. 17 illustrates the voltage profile of a battery having asolid-polymer electrolyte, showing a short duration of discharge at 50μA/cm², followed by discharging at 20 μA/cm² and charging at a currentdensity of 20 μA/cm², with an inset of a photograph of solid polymerelectrolytes, indicated by arrows.

Example 6 Charge and Discharge Cycles

An embodiment of a system useful for changing and discharging thedisclosed aluminum ion batteries is illustrated in FIG. 10 . In additionto standard galvanostatic (constant current) charge cycles,potentiostatic or a combination of potentiostatic and galvanostaticcharge cycles were shown to have an impact on the performance,specifically in terms of faster reaction kinetics (rate capability). Therange of voltages for potentiostatic charge was identified to liebetween 1.5 V and 2 V, while the optimum value was identified to beabout 1.8 V. At voltages greater than 2 V significant electrolysis wasobserved, confirmed by a rapid rise in currents.

The observed increase in rate capability could be attributed to thepresence of a stronger electromotive force to aid in the transport ofaluminum-based ions from the cathode back to the anode, which wouldcause few or no aluminum ions to be lost through side reactions in theelectrolyte and thereby a steady electric field is maintained to guidethe direction of flow of ions. In addition to galvanostatic,potentiostatic and galvanostatic-potentiostatic charge cycles, aconstant voltage sweep rate can be applied to charge the cell in certainembodiments. In certain embodiments, the dV/dt value of the constantvoltage sweep rate is from 0.01 mV/second to 100 mV/second.Galvanostatic charge and constant voltage sweep rate charge can both beapplied in conjunction with a final constant voltage charge to ensurecompletion of the charge cycle. Typically, in certain embodiments, thefinal constant voltage charge is maintained to achieve trickle chargeuntil the current drops below a pre-determined value ranging from 1% to50% of the current applied during galvanostatic charge cycle.

In certain embodiments, the discharge step can be a combination of highand low current density galvanostatic steps, allowing the cell chemistryto optimize coulombic efficiency and ensure maximum diffusion of activeions and its participation in electron-exchange reactions. Since thedischarge process is a function of the rate at which aluminum ionsdiffuse through manganese oxide, such a combination of high and lowcurrent prevents the build-up of localized charge at thecathode-electrolyte interface and optimizes the efficiency of the cell.

While not wishing to be bound by theory, it is believed that as smallregions at the cathode-electrolyte interface continue to build up chargeat relatively high current densities, the flow of ions gets impeded andthe reaction kinetics become slower. Therefore, a method that followssuch a high current draw with a short period of low current densitydischarge enables dissipation of this localized charge build-up, helpingthe ions diffuse through the surface and into the longitudinal depths ofthe cathode and as a result, freeing up the surface of the cathode forsubsequent ions to diffuse through to the bull of cathode. It isbelieved that at higher current densities, aluminum ions do not havesufficient time to diffuse through the bulk of cathode, resulting in alocalized charge build-up at the cathode-electrolyte interface. As thehigh current density is momentarily replaced by a lower current density,aluminum ions begin diffusing through the bulk of the cathode, resultingin a reduction in the localized charge build-up at thecathode-electrolyte interface.

A typical voltage profile produced using such a discharge profileincorporating a combination of low-current and high-current pulses isshown in FIG. 18 . FIG. 18 shows a discharge profile produced by acombination of low-current and high-current pulses. The battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 0.5 M aluminumnitrate (aq) electrolyte and a 25 μm thick polypropylene separator withan average pore size of 0.067 μm. The current densities were switchedbetween 100 A/g (low-current pulse) and 500 A/g (high-current pulse),where the current is normalized with respect to the mass of the cathode.Similar approaches can be used with a system such as the one illustratedin FIG. 10 to improve the overall performance of the battery.

Example 7 Electrochemical Delithiation

Electrochemical Delithiation. Lithium manganese oxide is mixed with apolymer binder, a thickening agent, or a mixture thereof combined with asolvent to form a slurry. In certain embodiments, the polymer binder isselected from the group consisting of polyvinylidene fluoride (PVDF),polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR) andmixtures thereof. In certain embodiments, the thickening agent is asuitable polysaccharide gum known to the art, such as carboxymethylcellulose (CMC). In certain embodiments, the mixture further comprises aconductive carbon additive, selected from the group consisting ofactivated carbon, Super-P carbon and mixtures thereof. In certainembodiments, to form a non-aqueous slurry, the mixture is combined witha suitable non-aqueous solvent such as N-methyl pyrrolidone. In certainembodiments, to form an aqueous slurry, the mixture is combined with asuitable solvents such as water, ethanol or a mixture of water andethanol.

In certain embodiments, a mixture to be used to form a non-aqueousslurry comprises polymer binders such as PVDF and PTFE in concentrationsranging from 0-20 percent by weight (wt %), based on the total weight ofthe mixture. In certain embodiments, the mixture comprises 2-20 wt % ofa polymer binder, based on the total weight of the mixture. In certainembodiments, a mixture to be used to form an aqueous slurry comprisespolymer binders such as SBR or polymethyl methacrylate (PMMA) inconcentrations ranging from 0-20 wt %, based on the total weight of themixture. Thickening agents such as carboxymethyl cellulose (CMC) mayalso be introduced in the mixture in concentrations ranging from 0-20 wt%, based on the total weight of the mixture. Conductive additives suchas activated carbon and Super-P carbon, when present, can be included inthe mixture at concentrations up to 50 wt %, based on the total weightof the mixture. The amount of lithium manganese oxide in the mixture canconstitute up to 98 wt %, based on the total weight of the mixture. Incertain embodiments, the amount of lithium manganese oxide in themixture is 2-98%, based on the total weight of the mixture.

Aqueous Slurry. A mixture was made by combining 4 wt % CMC, 6 wt % SBR,10% wt Super-P conductive carbon and 80 wt % lithium manganese oxide,based on the total weight of the mixture. An aqueous slurry was thenprepared by adding the mixture to deionized water and stirring at roomtemperature. The viscosity of the resulting slurry was controlled bymaintaining the solvent volume to ˜2.5-4 mL per gram of mixture. Theaqueous slurry was mixed (Thinky Planetary Centrifugal Mixer ARE-31) forup to 120 minutes at rotational speeds of up to 10,000 rpm before beingcast on to a metal substrate. In certain embodiments, the substrate isaluminum. In certain other embodiments, the substrate is stainlesssteel. Other suitable substrates include nickel, copper and pyrolyticgraphite. The slurry was cast on the substrate using a standard doctorblade coating method.

Non-aqueous Slurry. A mixture was made by combining 10 wt % PVDF, 10 wt% Super-P conductive carbon and 80 wt % lithium manganese oxide byweight, based on the total weight of the mixture. A non-aqueous solutionwas then prepared by adding the mixture to N-methyl pyrrolidone. Theviscosity of the resulting slurry was controlled by maintaining thesolvent volume to ˜2.5-4 mL per gram of mixture. The non-aqueous slurrywas mixed (Thinky Planetary Centrifugal Mixer ARE-31) at roomtemperature for up to 120 minutes and at rotational speeds of up to10,000 rpm before casting the slurry on to a metal substrate. In certainembodiments, the substrate is aluminum. In certain other embodiments,the substrate is stainless steel. Other suitable substrates includenickel, copper and pyrolytic graphite. The slurry was cast on thesubstrate using a standard doctor blade coating method. Upon drying ofthe coating, the cathode is assembled against a lithium foil electrode,separated by a polypropylene separator and immersed in a standardlithium ion electrolyte such as lithium hexafluorophosphate solution inethylene carbonate and diethyl carbonate (1.0 M LiPF6 in EC:Dec.=50/50(v/v), battery grade, Sigma-Aldrich).

A constant voltage of up to 6 V is then applied to allow delithiation ofthe lithium manganese oxide cathode. An open-circuit voltage reading ofabove 3 V is indicative of successful delithiation. Following this, thecathode is removed, washed repeatedly with dimethyl carbonate and water,and dried to obtain electrochemically delithiated manganese oxidecathodes.

Example 8 Surface Etching

Surface Etching of MnO₂ with Hydroxide Treatment in Combination withBull Delithiation to Increase Porosity. The performance of MnO₂ cathodescan be increased in terms of both power density (rate capability) andenergy density (capacity) through the incorporation of additionalstructural porosity. Without wishing to be bound by theory, it isbelieved that porosity allows electrolytic pathways for active ions toreach reaction sites within the cathode, thereby overcoming diffusionlimitations (the time active ions would take to diffuse through the bullof the cathode material), while also ensuring that more active reactionsites are now available for the electrochemical reactions.

An hydroxide-based etching technique was used to improve the porosity ofthe MnO₂ cathodes. In certain embodiments, lithium manganese oxidepowder is immersed in a 0.1 M to 4 M solution of a hydroxide selectedfrom the group consisting of lithium hydroxide (LiOH), potassiumhydroxide (KOH), sodium hydroxide (NaOH), tetramethyl ammonium hydroxide(TMOH) and mixtures thereof. In certain embodiments, the concentrationof the mixture ranges between 0.1 g of lithium manganese oxide in 1 mLof the hydroxide solution to 0.1 g of lithium manganese oxide in 10 mLof the hydroxide solution. The hydroxide solution can comprise aqueoussolvents, such as water, organic solvents, such as ethanol, or N-methylpyrrolidone, or a mixture thereof.

In further embodiments, coated lithium manganese oxide cathodes,free-standing or adhering to a current collector substrate, can bedirectly treated with an aqueous or organic solution of a 0.1 M to 4 Msolution of a hydroxide selected from the group consisting of lithiumhydroxide (LiOH), potassium hydroxide (KOH), sodium hydroxide (NaOH),tetramethyl ammonium hydroxide (TMOH) and mixtures thereof.

FIG. 19 shows discharge voltage profiles illustrating that a combinationof hydroxide etching and delithiation of a MnO₂ cathode along withincorporation of LiOH in the electrolyte can produce about two-foldincrease in current densities. Curve 1 was obtained from a batteryhaving a 0.1 mAh rating discharged for 8 hours at a current density of10 μA/cm². Curve 2 was obtained from a battery having a 0.1 mAh ratingdischarged for 5 hours at a current density of 20 μA/cm². Each batterywas assembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M Al(NO₃)₃ and 2 M LiOH (aq) electrolyte.

Hydroxide based surface etching can be combined with acid-baseddelithiation or electrochemical delithiation to improve batteryperformance. As shown in FIG. 20 , the average discharge potential of acathode produced by a combination of these methods about 1.07 V. FIG. 20shows a discharging voltage profile (curve 1) and a charging voltageprofile (curve 2) of a battery having a cathode comprising MnO₂synthesized by a combination of acid-based (nitric acid) delithiationfollowed by 2M LiOH treatment of the MnO₂ coated cathode, where thedischarge cut-off (dashed line) has been set at 1 V. The battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, a cathodecomprising acid-treated lithium manganese oxide, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M Al(NO₃)₃ (aq) electrolyte.

In other embodiments, cathodes produced by acid-based delithiation alonewere shown to have an average discharge potential ranging between 0.9 Vand 1.1 V. Since the energy density is a product of charge stored(capacity) and nominal voltage, an increased discharge potentialdirectly corresponds to an improvement in energy density.

FIG. 21 shows a discharging voltage profiles of batteries havingdifferent treatments of the delithiated MnO₂ cathode. Curve 1 is thedischarging voltage profile of a battery having a cathode comprisingMnO₂ that was delithiated using nitric acid. Curve 2 is the dischargingvoltage profile of a battery having a cathode comprising MnO₂ that wasdelithiated electrochemical delithiation. Curve 3 is the dischargingvoltage profile of a battery having a cathode comprising MnO₂ that wasdelithiated using nitric acid, followed by treatment of the cathode with2M LiOH. Each battery was assembled in a 2032 coin cell format and hadan anode comprising an aluminum foil treated with LiOH as described inExample 1, a cathode comprising acid-treated lithium manganese oxide, a25 μm thick polypropylene separator with an average pore size of 0.067μm, and a 0.5 M Al(NO₃)₃ (aq) electrolyte.

Example 9 Production of Porous Manganese Dioxide

Production of Porous Manganese Dioxide. As the cross-sectional thicknessof the cathode is scaled up, provisions have to be made to compensatefor the longer diffusion times for the active ions to participate in theelectrochemical reaction. One such strategy is to introduce pores intothe cathode structure that would facilitate improved electrolytewettability, thereby providing an electrolytic pathway for the ions todiffuse through the cathode, rather than relying on the slow inter-sheetdiffusion process. Another approach to ensure improved porosity andhence, better rate capability and access to active reaction sites withinthe cathode is through introduction of porosity during the production ofmanganese oxide for use in cathodes, as described in detail below.

Porosity may be introduced in the electrodes through incorporation of atleast one sacrificial template selected from the group consisting ofzeolite, MCM-41, silicon dioxide, silicon, copper, copper oxide, nickel,nickel oxide, aluminum, aluminum oxide, tungsten, titanium, titaniumnitride, gold, chromium, indium titanium oxide and mixtures thereof,followed by etching the sacrificial template either before or aftercoating the mixture of electrode material plus sacrificial template onto a current collector. Suitable etchants include acetic acid,phosphoric acid, hydrochloric acid, sulfuric acid, nitric acid,hydrofluoric acid, buffer oxide, potassium hydroxide, sodium hydroxide,lithium hydroxide, tetramethyl ammonium hydroxide, hydrogen peroxide,ethylenediamine pyrocatechol, water, aqua regia, iodine, potassiumiodide and mixtures thereof. This method can be used to introduceporosity in both anodes and cathodes, except for when metal foils aredirectly used as the electrode.

Template-Based Production of MnO₂: Manganese oxide produced by eitheracid-based delithiation or electrochemical delithiation was mixed with aporous template such as MCM-41. MCM-41 (Mobil Composition of Matter No.41) is a mesoporous material with a hierarchical structure from a familyof silicate solids that were first developed by researchers at Mobil OilCorporation for use as catalysts or catalyst supports. The concentrationof the porous template is between 5-50 wt %, based on the total weightof the MCM-41 and delithiated manganese oxide mixture. The mixture wasthen ball-milled for 5-120 minutes to obtain porous manganese oxide. TheMCM-41 content can be subjected to calcination, whereby the powder issubjected to temperatures ranging between 200° C. and 800° C. in aninert environment. MCM-41 can be further partially or completely etchedthrough KOH or buffered oxide etching methods. KOH etchant can compriseof 5-60 wt. % of KOH in water. Buffered oxide etchant comprises 3:1 to9:1 volume ratio of 5-40 wt % ammonium fluoride in water and 5-49 wt %of hydrofluoric acid in water. Following the etching process, the finalproduct is washed repeatedly with deionized water to remove tracecontaminants.

Manganese oxide produced by either acid-based delithiation orelectrochemical delithiation can also be mixed with zeolite to obtain aporous cathode structure. Zeolite is a micro-porous aluminosilicatemineral that can be mixed with the cathode material to achieve porosity.The concentration of zeolite varies between 1-30 wt % based on the totalweight of zeolite and delithiated manganese oxide mixture. In addition,additives such as polyvinyl alcohol may be introduced in concentrationsbetween 1-30 wt % to further improve the hydrophilicity. The mixture wasthen ball-milled for 5-120 minutes to obtain porous hydrophilicmanganese oxide. The zeolite template can be partially or completelyremoved by KOH etching or buffered oxide etching. KOH etchant cancomprise of 5-60 wt. % of KOH in water. Buffered oxide etchant comprises3:1 to 9:1 volume ratio of 5-40 wt % ammonium fluoride in water and 5-49wt % of hydrofluoric acid in water. Following the etching process, thefinal product is washed repeatedly with deionized water to remove tracecontaminants.

In-situ Growth of MnO₂ on Porous Substrates: Porosity may also beintroduced by growing manganese oxide directly on a porous substrateincluding silicon, silicon dioxide, aluminum, aluminum oxide, tin, tinoxide, copper, copper oxide, nickel, nickel oxide, titanium, titaniumoxide, titanium nitride, titanium carbide, carbon, tungsten, gold,platinum, chromium, cobalt and indium titanium oxide. The poroussubstrates may have the morphology of mesh, wires, pillars, spirals orfibers. The porous substrates may or may not be removed using suitableetchants. Suitable etchants include acetic acid, phosphoric acid,hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, bufferoxide, potassium hydroxide, sodium hydroxide, lithium hydroxide,tetramethyl ammonium hydroxide, hydrogen peroxide, ethylenediaminepyrocatechol, water, aqua regia, iodine, potassium iodide and mixturesthereof. When the porous substrate is left unremoved or partiallyunremoved, specifically when the substrate is a conductive component,the substrate acts as an ion conducting pathway and participates inelectron transfer kinetics.

The cathode materials (δ and λ MnO₂) were synthesized directly on aporous SiO₂ template. In one example, δ-MnO₂ was synthesized by thereaction of Mn₃O₄ in a 0.5 M ammonium persulfate solution. The pH of thesolution was maintained at 8-9 during the reaction. The porous SiO₂template was mixed in the above solution to deposit δ-MnO₂ on thetemplate. The solution was then refluxed at 80° C. to synthesize δ-MnO₂.Chemical synthesis of λ-MnO₂ was carried out by a reflux reactionmethod. Manganese acetate was reacted in the presence ofdimethylsulfoxide (DMSO) and hydrazine. The porous template was mixed inthe above solution for direct deposition of λ-MnO₂ on the template. Thesolution was then refluxed at about 140° C. The end product was thenwashed with water after which it was dried in a vacuum oven to obtainthe final powder for use in cathodes.

Synthesis of Oxygen-Rich MnO₂: In addition to the manganese oxidesynthesis approaches described above, alternate oxygen-rich manganeseoxide cathodes were produced. In certain embodiments, the porousmanganese dioxide produced can be further treated by surface etchingwith hydroxide compounds, as described in Example 8, above. While notwishing to be bound by theory, it is believed that the surface etchingtreatment serves to maximize porosity of the MnO₂ and increase access toactive reaction sites.

A porous-MnO₂ cathode was produced by mixing the MCM-41 sacrificialtemplate (10 nm to 40 μm particle size, 5 wt % to 90 wt % based on thetotal weight of the mixture) with chemically delithiated manganese oxidepowder. In certain embodiments, the MCM-41 is 5 wt % to 90 wt % of themixture, based on the total weight of the manganese oxide and MCM-41mixture. In certain embodiments, the manganese oxide is 10 wt % to 95 wt% of the mixture, based on the total weight of the manganese oxide andMCM-41 mixture. Conductive additives and binders may be added to thismixture manganese oxide and MCM-41 as described above in Example 7. Ifpresent, the conductive additives and binders are 1 wt %-20 wt % of thetotal weight of the mixture. The mixture is then added to asolvent—either aqueous (water) or non-aqueous (ethanol, methanol,tetrahydrofuran, N-methyl pyrrolidone and similar solvents). Theresultant slurry is subjected to planetary mixing at 2000 rpm or moreand for 2-20 minutes. The slurry is then cast on a substrate through adoctor-blade coating mechanism and allowed to dry to form a coatedcathode.

In certain embodiments, the coated cathode is then subjected to furtherchemical treatment to etch away the MCM-41 template. MCM-41 is primarilycomposed of SiO₂ and the etchants are selected accordingly. In certainembodiments, the etchant is a buffered mixture of 0.1-30 wt %hydrofluoric acid, 10-95 wt % water and 1-50 wt % ammonium fluoride. Incertain embodiments, the etchant is a buffered potassium hydroxidesolution comprising 5-80 wt % potassium hydroxide and 5-90 wt % of wateror organic solvents including but not limited to acetone, methanol,dimethyl sulfoxide and dimethyl formamide. Following the etchingprocess, the cathode is washed repeatedly with water and acid to removeimpurities and neutralize remnant hydroxyl ions. Once dried, the cathodeis ready to be assembled into battery.

Porous MnO₂ cathodes produced by the methods disclosed above haveimproved wettability compared to conventional MnO₂ cathodes. In the caseof the porous MnO₂ cathodes, the typical spherical profile of anelectrolyte droplet contacting the cathode is not observed, owing toexcellent seepage of the liquid throughout the structure, therebyindicating superior wettability characteristics.

In one example, a porous MnO₂ cathode was synthesized by using 80 wt %chemically delithiated MnO₂, 10 wt % MCM-41 and 10 wt % PVDF polymerbinder, mixed in N-methyl pyrrolidone solvent. The viscosity of theresulting slurry was controlled by maintaining the solvent volume to˜2.5-4 mL per gram of mixture. Following the casting of the electrodeand its subsequent drying, it was immersed in a solution comprising 40 w% KOH for 90 minutes in a furnace maintained at 75° C. At the end ofthis step, the cathode was retrieved from the solution, repeatedlywashed with deionized water and dried prior to use. The MnO₂ layer ofthe cathode was about 100 μm thick (range 80-120 μm). The cathode wasthen assembled in a coin cell configuration against an aluminum anode,separated by a polypropylene separator. The average discharge voltagewas measured to be 1.08 V at 10 μA/cm². FIG. 22 illustrates thedischarge voltage profile with the discharge set at a cut-off of 1 V ofa battery having a cathode with a 100 μm thick layer of porous MnO₂cathode, a 15 μm thick aluminum foil anode that had been treated withLiOH as described in Example 1, a 25 μm thick polypropylene separatorwith an average pore size of 0.067 μm, and a current density of about 10μA/cm². The electrolyte in the test example comprised 20 weight %aluminum nitrate in 80 weight % water.

Hydrogen Peroxide Treatment. Hydrogen peroxide (H₂O₂) treatment involvesthe reaction between H₂O₂ and MnO₂ cathodes, resulting in the reductionof the peroxide and evolution of oxygen and water. Increased wettabilityand ionic access through incorporation of water pockets may be realizedby treating delithiated manganese oxide with hydrogen peroxide,organophosphate esters and carbonitriles. Manganese oxide induceshydrolysis of the aforementioned additives, resulting in the generationof water pockets and oxygen. This treatment introduces water pocketswithin the core structure of the cathode coating that would otherwisenot be wetted by the electrolyte. In addition, it is believed that theevolution of oxygen can expand the inter-sheet spacing of the MnO₂ dueto a pressure build-up within the bulk cathode material.

In certain embodiments, the coated MnO₂ cathode is treated withpre-determined concentrations of H₂O₂, typically 1 wt % to 50 wt %aqueous solutions of H₂O₂ for 5-60 minutes room temperature to 80° C. Incertain embodiments, 1 wt %-30 wt % H₂O₂ can be incorporated into theelectrolyte as well. In certain embodiments, the volume of aqueousaluminum nitrate and hydrogen peroxide solution was maintained such thatthe resultant electrolyte was composed of 10 weight % hydrogen peroxide,20 weight % aluminum nitrate and 70 weight % water.

In one embodiment, a 100 μm (+/−10%) thick electrochemically delithiatedMnO₂ cathode was treated with 30% hydrogen peroxide (Sigma-Aldrich) for30 minutes. The electrolyte comprised 10 wt % H₂O₂, 20 wt % aluminumnitrate and 70 wt % deionized water. The cathode, along with theperoxide-based electrolyte, was assembled against a 15 μm aluminum foilanode treated as described in Example 1, glass microfiber separator with1 μm pore size. The cell was cycled at 10 μA/cm² and recorded a maximumachievable capacity of 0.25 mAh at an average discharge potential of1.08 V, as shown in FIG. 23 .

FIG. 23 illustrates the charge voltage profile (curve 1) and thedischarge voltage profile (curve 2) of a MnO₂ cathode with across-sectional thickness of 100 μm, assembled against a 15 μm thickaluminum foil that had been treated with LiOH, with a glass microfiberseparator and a current density of about 10 μA/cm². The cathode wastreated with H₂O₂ as described above and the electrolyte comprised 10weight % H₂O₂.

Example 10 Cathode Dopants

Incorporation of Dopants into the Cathodes. Addition of dopants to themanganese oxide cathode was also found to increase the discharging ratecapability and the charging rate capability. While not wishing to bebound by theory, it is believed that the increase was due tofacilitation of a more efficient electron transportation pathway.

Iodine doping of manganese oxide was carried out using a gas-phasepenetration technique. Manganese oxide powder was mixed with iodinecrystals (less than 50 wt %) and the mixture was then placed inside aclosed chamber and heated to about 50-200° C. (typically, above thesublimation temperature of iodine). In one such example, the temperatureat which sublimation of iodine was carried out was chosen to be 80° C.This causes iodine to sublime (transform from solid phase to gas phasedirectly) and a purple vapor can be seen inside the chamber. The vaporresults in doping the manganese oxide powder. However, the dopantconcentration is largely limited by the ability of iodine to penetratethe spinel structure of manganese oxide and therefore, the dopantconcentration is approximately about 10% or less of the weight of iodinecrystals used (for example, 100 mg of iodine mixed with 900 mg ofmanganese oxide is expected to result in 10 mg of iodine penetration,i.e., about 1% doping). In general, 1% doping is sufficient. However, inorder to achieve a greater dopant concentration, the ratio of the weightof iodine crystals and manganese oxide powder can be varied as desired.At the completion of the reaction, which usually takes 30 minutes toabout 2 hours, the chamber is re-heated at 80° C. in a vacuum furnace toensure any unreacted iodine crystal sublimes and is removed from thedoped manganese oxide powder. The process can be carried out on cathodeswith lithium manganese oxide as well as cathodes with coated manganeseoxide.

Iodine-doped manganese oxide was tested as an example and was found tohave an average discharge potential of about 1.16 V at about 20 μA/cm²,compared to 1.01 V for undoped manganese oxide cathodes tested at thesame current density. A standard polypropylene separator having 0.067 μmpores was used in testing for comparison with previously obtainedbaseline data. FIG. 24 is charge-discharge voltage profile ofacid-delithiated, iodine-doped manganese oxide cathode. The battery wasassembled in a 2032 coin cell format and had an anode comprising analuminum foil treated with LiOH as described in Example 1, anacid-delithiated, iodine-doped manganese oxide cathode, a 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and a 0.5M Al(NO₃)₃ (aq) electrolyte. Even at about 2-times the discharge currentdensity, the cathode displayed low charge and discharge hysteresis of 84mV and 129 mV respectively.

In addition to iodine as the dopant, alternate dopants can also beincorporated to achieve the same effect. Some options in this regardwould include but not be limited to nitrogen, boron and phosphorus.Apart from doping, other approaches to increase charge transfer kineticswould include broadly conductive materials incorporating platinum,silver, gold, titanium, carbon allotropes or similar catalysts andcombinations thereof (generally, <5 weight %) into the manganese oxidecathode. In order to achieve this, the catalyst may be simply mixed withthe manganese oxide powder and cast as a slurry or it can be depositedvia physical vapor deposition whereby a thin film of the catalyst wouldbe formed at the surface of the as-coated cathode.

Example 11 XPS Studies

X-ray photoelectron spectroscopy (XPS) measurements were carried out onthe surface of the anode and cathode following the completion of a deepdischarge reaction (aluminum-based ion penetration into manganese oxidecathode), in order to ascertain the reaction mechanism. In a typicalsample that was subjected to XPS measurements, both manganese oxide(MnO₂) cathode and aluminum (Al) anode showed significant presence ofoxides on the surface, corresponding to 61.3 atomic % and 62.9 atomic %,respectively. Aluminum was measured to be 12.1 atomic % and 15.6 atomic% at the surfaces of MnO₂ and Al respectively. In addition to aluminumand oxygen, the cathode and anode samples also showed traces of carbon(in the form of hydrocarbons, oxides and nitrides, attributed to polymerbinders and carbon-based conductive additives present in the cathode aswell as atmospheric contamination and adsorption on both anode andcathode surfaces), nitrogen (primarily in the form of nitrates andattributed to solid electrolyte interphase formation reaction betweenelectrode surface and aluminum nitrate constituents in the electrolyte),fluorine (electrolyte used during electrochemical delithiation oflithium manganese oxide) and manganese (present in cathodes; traceamounts of manganese observed at the anode surface is attributed toelectrolytic dissolution and transportation of manganese dioxide owingto deep discharge parameters). The XPS measurements are shown in FIG. 25(anode) and FIG. 26 (cathode).

Analyzing the atomic concentrations and the state of bonds, it ispossible to make an accurate estimation of the state of aluminum at boththe anode and cathode sites. While it is not possible to accuratelydistinguish between Al(OH)₃, Al₂O₃ and AlOOH bonds, the surfaceconcentration of MnO₂ and Al(NO₃)₃ can be accurately identified in anXPS measurement. The Gibbs Free Energy (G) values of Al(OH)₃, Al₂O₃ andAlOOH are −1306 kJ/mol, −1576 kJ/mol and −918 kJ/mol respectively,indicating highly spontaneous formation reactions and therefore, asignificant likelihood of the presence of one, two or all three of thesecompounds.

The discharge reaction involving the reduction of trivalent aluminumions to hydroxyaluminate,Al(OH)₄ ¹⁻→Al(OH)₃+OH¹⁻+3e  (12)

is calculated to occur at an ideal reaction potential of about 0.6 V.Similarly, the charge reaction that results in the release ofmultivalent aluminum ions,Al(OH)₃+3e→Al³⁺+3OH¹⁻  (13)is estimated to have a theoretical reaction potential of 1.19 V. Thepractical operating voltage window observed in the proposed aluminum ioncells typically lies between a minimum and maximum range of 0.2 V and 2Vrespectively, thereby corresponding to and encompassing the theoreticalreaction potentials calculated above. One of ordinary skill wouldrecognize that non-ideality factors such as atmospheric humidity,temperature, contamination, pH, internal resistance and other similarparameters can often contribute to a significant deviation of practicalreaction potentials from the theoretical values. This observationtherefore suggests that the concentration of Al(OH)₃ may be higher thanthat of both Al₂O₃ and AlOOH. Consequently, this observation is alsosupported by the XPS measurements. One of ordinary skill would recognizethat each of Al(OH)₃, Al₂O₃ and AlOOH can potentially transform into theother state based on the atmospheric condition, presence of moisture,electrolyte pH and other similar parameters. Examples of such reactionswould include:2Al(OH)₃→Al₂O₃+3H₂O  (14), andAl₂O₃+3H₂O→2AlOOH  (15).

Therefore, while the evidence presented in FIG. 25 and FIG. 26 suggeststhat aluminum hydroxide is the primary product in the dischargereaction, alternate discharge products such as Al₂O₃ and AlOOH may alsobe present.

Example 12 Other Cathodes

Apart from manganese oxide cathodes, titanium oxide cathodes were alsotested successfully. In fact, the host of cathodes capable ofintercalating with aluminum hydroxide would include compounds withlargely similar properties including but not limited to alpha, beta andlambda phases of manganese oxide, oxides of alternative metals(including but not limited to titanium oxide, tin oxide, iron oxide,vanadium oxide, molybdenum oxide, cobalt oxide), sulfides of alternativemetals (including but not limited to molybdenum sulfide, tungstensulfide, iron sulfide) or combination of at least one of such materials.In this particular example in FIG. 27 , titanium oxide cathodes weredischarged successfully within a voltage window of 0.2 V and 1.5 V.

FIG. 27 shows a charge/discharge voltage profile of a titanium oxidecathode assembled against an anode comprising an aluminum foil treatedwith LiOH as described in Example 1, using a standard 25 μm thickpolypropylene separator with an average pore size of 0.067 μm, and 0.5 MAl(NO₃)₃ electrolyte.

Example 13 Organic Electrolytes

Aluminum ion batteries were also tested in an organic electrolyte. Theanode comprised hydroxide-treated aluminum foil, the separator was a 25μm thick polypropylene separator with an average pore size of 0.067 μmand the cathode comprised acid-delithiated manganese dioxide. Theelectrolyte comprised 20 wt. % aluminum nitrate and 10 wt. % lithiumbis(trifluoromethanesulfonyl)imide in 35 wt. % diethyl carbonate and 35wt. % dimethyl carbonate. The batteries displayed an average operatingpotential during the charging cycle of 3.9 V and an average operatingpotential during the discharging cycle of 3.4 V (FIG. 28 ). Such asystem allows a marked improvement in energy density with ˜3-foldincrease in operating voltage.

Example 14 Methanol Additive in Electrolyte

Incorporation of methanol in the electrolyte to a final concentration ofabout 2-90%, typically about 10% was found to improve the dischargevoltage stability (FIG. 29 ). While not wishing to be bound by theory,it is believed that methanol (CH₃OH) acts as a hydroxide formationpromoter and therefore facilitates aluminum hydroxide formation andtransport, thereby reducing the loss of aluminum ions in the electrolytethrough unwanted side reactions. FIG. 29 compares the voltage profile ofan aluminum ion battery having a 0.5 M Al(NO₃)₃ (aq) electrolyte (curve1, filled triangles) to the voltage profile of an aluminum ion batteryhaving a 0.45 M Al(NO₃)₃ (aq) electrolyte containing 10% methanol (curve2, filled circles). In both batteries the anode comprisedhydroxide-treated aluminum foil and the cathode comprisedacid-delithiated manganese oxide.

Example 15 Magnetically-Induced Cathode Porosity

In order to align manganese oxide sheets to achieve maximum porosity,magnetic iron oxide particles were mixed in the slurry to form thecathode, in a weight ratio of 5% iron oxide nanoparticles (<50 nm,Sigma-Aldrich, St. Louis, Mo.), 75% acid delithiated manganese oxide,10% conductive carbon and 10% PVDF binder. The mixture was added toN-methyl pyrrolidone and coated on a metal substrate using doctor-bladeand slot-die coating. The slurry-coated substrate and at least onemagnet were assembled in a closed chamber with a spacer placed betweenthe magnet(s) and the surface of the slurry to avoid direct contactbetween the slurry and the magnet(s). The magnets (with a net magneticforce of 150 lbf) were placed above the wet slurry, at a distance ofabout 1 cm from the surface of the wet slurry. As the slurry dried,magnetic iron oxide particles mixed with manganese oxide were pulled bythe magnet in the direction of the magnetic field and in the process,aligned the manganese oxide particles in the slurry uniformly and alongthe direction of the magnetic field. While not wishing to be bound bytheory, the cathodes prepared using this method displayed higherwettability with aqueous electrolytes than observed with cathodesprepared using other methods.

In certain embodiments, nickel-plated neodymium-iron-boron magnets wereused, but other magnets of similar size, mass and pull force would besuitable. Several magnets can be aligned so that the net magnetic pullforce is a result of the summation of the pull forces of the individualmagnets. The pull force of individual magnets was supplied by thevendor. A total pull force of about 10 lbf to 200 lbf is the idealrange. Magnetic pull forces less than 10 lbf are too low to properlyalign iron oxide nanoparticles, while magnets with pull forces greaterthan 200 lbf are difficult to handle in a laboratory environment andunnecessarily high for the desired nanoparticle alignment. The spacingbetween the slurry surface and the magnets can be adjusted as needed,with a larger spacing being suitable for higher magnetic pull forces.The drying time of the slurry can be adjusted by the humidity within theclosed chamber. A high magnetic pull force can permit fasted dryingtimes, while a lower magnetic pull force necessitates slower dryingtimes.

While the disclosure has been described with reference to an exemplaryembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the disclosure. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the disclosure without departing fromthe essential scope thereof. Therefore, it is intended that thedisclosure not be limited to the particular embodiment disclosed as thebest mode contemplated for carrying out this disclosure, but that thedisclosure will include all embodiments falling within the scope of theappended claims.

The invention claimed is:
 1. A rechargeable aluminum ion battery comprising: an anode comprising aluminum, an aluminum alloy or an aluminum compound, wherein the anode has an oxygen-rich surface; a cathode that comprises a bulk cathode material selected from the group consisting of a manganese oxide; lithium manganese oxide; acid-treated lithium manganese oxide; electrochemically delithiated lithium manganese oxide; hydrothermally delithiated lithium manganese oxide; a lithium metal manganese oxide; an acid-treated lithium metal manganese oxide; manganese dioxide; and electrolytic manganese dioxide, wherein the bulk cathode material has a structure that accommodates insertion of an ion comprising aluminum; a porous separator comprising an electrically insulating material that prevents direct contact of the anode and the cathode; and an electrolyte comprising a solvent and an aluminum salt, wherein the electrolyte is in contact with the anode and the cathode, wherein charge is carried by the ion comprising aluminum, and wherein the porous separator has a porosity that allows movement of the ion comprising aluminum between the anode and the cathode.
 2. The battery of claim 1 wherein the ion comprising aluminum is selected from the group consisting of Al³⁺, Al(OH)₄ ¹⁻, AlCl₄ ¹⁻, AlH₄ ¹⁻, AlF₆ ¹⁻, Al(NO₃)₄ ¹⁻, Al(SO₄)₂ ¹⁻, AlH₄ ¹⁻, AlF₄ ¹⁻, AlBr₄ ¹⁻, AlI₄ ¹⁻, Al(ClO₄)₄ ¹⁻, Al(PF₆)₄ ¹⁻, AlO₂ ¹⁻, Al(BF₄)₄ ¹⁻, and mixtures thereof.
 3. The battery of claim 1 wherein the solvent comprises at least one compound selected from the group consisting of water, hydrogen peroxide, methanol, ethanol, isopropanol, acetone, tetrahydrofuran, N-methyl pyrrolidone, a substituted or unsubstituted C₁-C₄ straight chain or branched alkyl carbonate, a substituted or unsubstituted C₁-C₄ straight chain or branched alkene carbonate, an ionic liquid and mixtures thereof.
 4. The battery of claim 3 wherein the electrolyte comprises the ionic liquid and the ionic liquid comprises at least one cation selected from the group consisting of a substituted or unsubstituted quaternary ammonium ion, substituted or unsubstituted imidazolium ion, a substituted or unsubstituted pyrrolidinium, a substituted or unsubstituted piperdinium, and a substituted or unsubstituted phosphonium ion, and at least one anion selected from the group consisting of a halide ion, a carbonate ion, a nitrate ion, a sulfate ion, a cyanate ion, a dicyanamide ion, a substituted or unsubstituted borate ion, a substituted or unsubstituted acetate ion, a substituted or unsubstituted imide ion, a substituted or unsubstituted amide ion, a substituted or unsubstituted sulfonate ion, and a substituted or unsubstituted benzoate ion, wherein when substituted, the substituent is at least one moiety selected from the group consisting of halide, carbonate, sulfate, substituted or unsubstituted C₁-C₄ straight chain or branched alkyl, substituted or unsubstituted C₁-C₄ straight chain or branched allene, substituted or unsubstituted C₄-C₆ cycloalkyl, and substituted or unsubstituted C₆-C₈ aryl, and mixtures thereof.
 5. The battery of claim 1 wherein the solvent comprises at least one compound selected from the group consisting of water, hydrogen peroxide, methanol, ethanol, isopropanol, acetone, tetrahydrofuran, N-methyl pyrrolidone, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, an imidazolium acetate, an imidazolium aluminate, an imidazolium carbonate, an imidazolium cyanate, an imidazolium dicyanamide, an imidazolium halide, an imidazolium hexafluorophosphate, an imidazolium imide, an imidazolium nitrate, an imidazolium phosphate, an imidazolium sulfate, an imidazolium sulfonate, an imidazolium tetrafluoroborate, an imidazolium tosylate, a pyrrolidinium halide, a pyrrolidinium imide, a pyrrolidinium tetrafluoroborate, a tetrabutylammonium benzoate, a tetrabutylammonium cyanate, a tetrabutylammonium halide, a tetrabutylammonium sulfonate, a tetrabutylammonium trifluoroacetate, a phosphonium tetrafluoroborate, a phosphonium halide, a phosphonium sulfonate, a phosphonium tosylate and mixtures thereof.
 6. The battery of claim 1 wherein the aluminum salt comprises at least one compound selected from the group consisting of aluminum acetate, aluminum acetoacetate, aluminum bromide, aluminum bromide hexahydrate, aluminum carbonate, aluminum chloride, aluminum chlorohydrate, aluminum clofibrate, aluminum diacetate, aluminum diethyl phosphinate, aluminum fluoride, aluminum fluoride trihydrate, aluminum formate, aluminum hydroxide, aluminum iodide, aluminum iodide hexahydrate, aluminum molybdate, aluminum nitrate, aluminum nitrate nonahydrate, aluminum perchlorate, aluminum phosphate, aluminum silicate, aluminum sulfate, aluminum sulfide, aluminoxane, ammonium aluminum sulfate, ammonium hexafluoroaluminate and mixtures thereof.
 7. The battery of claim 6 wherein the electrolyte further comprises lithium bis(trifluoromethanesulfonyl)imide, diethyl carbonate and dimethyl carbonate.
 8. The battery of claim 2 wherein the electrolyte further comprises at least one ion selected from the group consisting of Li¹⁺, Cl¹⁻, and CH₃ ¹⁺.
 9. The battery of claim 1 wherein the electrolyte further comprises at least one compound selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, calcium hydroxide, magnesium hydroxide, rubidium oxide, cesium oxide, polytetrafluoroethylene, polyethylene oxide, acetonitrile butadiene styrene, styrene butadiene rubber, ethyl vinyl acetate, polyvinyl alcohol, poly(vinylidene fluoride-co-hexafluoropropylene), polymethyl methacrylate and mixtures thereof.
 10. The battery of claim 1 wherein the anode comprises the aluminum compound and the aluminum compound is selected from the group consisting of an aluminum transition metal oxide (Al_(x)M_(y)O_(z), where M is a transition metal selected from the group consisting of iron, vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive); an aluminum transition metal sulfide (Al_(x)M_(y)S_(z), where M is a transition metal selected from the group consisting of iron, vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive); an aluminum transition metal nitride (Al_(x)M_(y)N_(z), where M is a transition metal selected from the group consisting of iron, vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive); an aluminum transition metal carbide (Al_(x)M_(y)C_(z), where M is a transition metal selected from the group consisting of iron, vanadium, titanium, molybdenum, copper, nickel, zinc, tungsten, manganese, chromium, and cobalt, and x, y, and z range from 0 to 8, inclusive); aluminum lithium cobalt oxide, lithium aluminum hydride, sodium aluminum hydride, potassium aluminum fluoride, aluminum indium oxide, aluminum gallium oxide, aluminum indium sulfide, aluminum gallium sulfide, aluminum indium nitride, aluminum gallium nitride, and mixtures thereof.
 11. The battery of claim 1 wherein the anode comprises aluminum coated with a metal oxide layer, aluminum coated with a metal phosphate layer, aluminum coated with a metal nitride layer, aluminum coated with a metal sulfide layer, aluminum coated with a metal carbide layer, or aluminum coated with a graphite layer.
 12. The battery of claim 1 wherein the anode is coated with a layer of ionically conducting, insulating or electrically conductive polymer selected from the group consisting of a polyaniline, a polyacetylene, a polyphenylene vinylene, a parylene, a polypyrrole, a polythiophene, a polyphenylene sulfide, a polystyrene, a polyvinyl alcohol, a polyethylene oxide, a polymethyl methacrylate, graphite and mixtures thereof.
 13. The battery of claim 1 wherein the anode further comprises a redox catalyst such as platinum, a compound comprising zirconium, vanadium pentoxide, silver oxide, iron oxide, molybdenum oxide, bismuth oxide, bismuth-molybdenum oxide, iron molybdenum oxide, palladium salts, copper salts, cobalt salts, manganese salts, Prussian blue analogs such as cobalt hexacyanocobaltate or manganese hexacyanocobaltate, and mixtures thereof.
 14. The battery of claim 1 wherein the bulk cathode material comprises a member selected from the group consisting of: a lithium metal manganese oxide, wherein the metal is selected from the group consisting of nickel, cobalt, aluminum, chromium, sodium, potassium, iron, copper, tin, titanium, tungsten, zinc, platinum and mixtures thereof; and an acid-treated lithium metal manganese oxide, wherein the metal is selected from the group consisting of nickel, cobalt, aluminum, chromium, sodium, potassium, iron, copper, tin, titanium, tungsten, zinc, platinum and mixtures thereof.
 15. The battery of claim 1 wherein the bulk cathode material comprises acid-treated lithium manganese oxide that has been treated using iron oxide nanoparticles in a magnetic field.
 16. The battery of claim 1 wherein the cathode further comprises a redox catalyst selected from the group consisting of platinum, a compound comprising zirconium, vanadium pentoxide, silver oxide, iron oxide, molybdenum oxide, bismuth oxide, bismuth-molybdenum oxide, iron molybdenum oxide, palladium salts, copper salts, cobalt salts, manganese salts, Prussian blue analogs such as cobalt hexacyanocobaltate or manganese hexacyanocobaltate, and mixtures thereof.
 17. A system comprising a battery according to claim 1 wherein the battery is operatively connected to a controller, and wherein the controller is adapted to be operatively connected to a source of electrical power and to a load.
 18. The system of claim 17 wherein the controller is effective to control the charging of the battery by the source of electrical power.
 19. The system of claim 17 wherein the controller is effective to control the discharging of the battery by the load.
 20. The system of claim 17 wherein the controller is adapted to provide a discharge pattern that is a combination of high and low current density galvanostatic steps.
 21. The system of claim 17 wherein the source of electrical power is a solar panel or wind-powered generator.
 22. The system of claim 17 wherein the load is a local electrical load or a power distribution grid.
 23. The battery of claim 1, wherein the oxygen-rich surface of the anode is at least 60 atomic % oxygen.
 24. The battery of claim 1, wherein the oxygen-rich surface is non-native.
 25. The battery of claim 1, wherein the oxygen-rich surface forms during electrochemical cycling.
 26. The battery of claim 1, wherein the solvent comprises methanol.
 27. The battery of claim 1, wherein the cathode comprises sheets.
 28. The battery of claim 1, wherein the ion comprising aluminum is polyatomic.
 29. The battery of claim 1, wherein the solvent is water and wherein the bulk cathode material is at least partially hydrophilic.
 30. The battery of claim 1, wherein the bulk cathode material has sufficient porosity and inter-sheet voids to accommodate insertion and intercalation of the ion comprising aluminum. 